Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Tony Lindgren t...@atomide.com writes:
* Kevin Hilman khil...@deeprootsystems.com [121012 13:34]:
I'm not conviced (yet) that a mismatch is the root cause. Yes, that's
what the author of $SUBJECT patch assumed and stated, but I'm not
pursuaded.
If it's an improperly configured mux issue, then the UART will break
whenever the device is actually omap_device_enable'd, whether in the
driver or in the bus layer.
I tried booting n800 here with CONFIG_OMAP_MUX disabled, and no
change. Serial console output stops right when the console initializes.
OK, since it's not mux, and since those who actually maintain this
driver don't seem to be taking care of this, I did some digging today.
Russell is right. It's a mismatch between assumed runtime PM state
(disabled) and actual HW state.
During init, all omap_devices are idled by default, so that they are
correctly in the state that the runtime PM framework will later expect
them to be. That is, all devices *except* the console UART. For that
one, we use the special hwmod flag to not idle/reset the UART since that
will cause problems during earlyprintk usage, and the switch between
the earlyprintk console and the real console driver.
Since the console uart was left enabled during init, it needs to be
fully enabled and the runtime PM status set accordingly.
The patch below does this, and works fine on 2420/n810, as well as on
3530/Overo, 3730/OveroSTORM, 3730/Beagle-XM and 4430/PandaES.
Will send patch with a proper changelog shortly,
Kevin
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 0405c81..37b5dbe 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -327,6 +327,11 @@ void __init omap_serial_init_port(struct omap_board_data
*bdata,
if ((console_uart_id == bdata-id) no_console_suspend)
omap_device_disable_idle_on_suspend(pdev);
+ if (console_uart_id == bdata-id) {
+ omap_device_enable(pdev);
+ pm_runtime_set_active(pdev-dev);
+ }
+
oh-mux = omap_hwmod_mux_init(bdata-pads, bdata-pads_cnt);
oh-dev_attr = uart;
--
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Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi Paul, There are On Thursday 11 October 2012 11:58 PM, Paul Walmsley wrote: Hi Sourav, Felipe, any progress on fixing the N800 problem? Would be good to keep it booting since we use it as our primary 2420 test platform. - Paul The patch sent inlined below might help us to get rid of the serial init issue. Unfortunately, I dont have a N800 board with me to test it and will require your help to do so. --- From: Sourav Poddar sourav.pod...@ti.com Date: Wed, 1 Aug 2012 15:44:12 +0530 Subject: [RFT/PATCH] serial: omap: Fix N800 serial init issue. This patch might solve the N800 serial init issue. This patch will also give pointers if there is any mux settings issue with N800 OR a mismatch between the initial harware state, runtime PM state and omap hwmod state. I don't have a N800 schematics to check about the mux settings getting used. The observation on beagle board XM with this patch on different boards looks flaky, so your feedback on beagle board will also be very helpful. Cc: Felipe Balbi ba...@ti.com Signed-off-by: Sourav Poddar sourav.pod...@ti.com --- drivers/tty/serial/omap-serial.c |1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_use_autosuspend(pdev-dev); pm_runtime_set_autosuspend_delay(pdev-dev, -- 1.7.1 -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Sourav sourav.pod...@ti.com writes: Hi Paul, There are On Thursday 11 October 2012 11:58 PM, Paul Walmsley wrote: Hi Sourav, Felipe, any progress on fixing the N800 problem? Would be good to keep it booting since we use it as our primary 2420 test platform. - Paul The patch sent inlined below might help us to get rid of the serial init issue. Unfortunately, I dont have a N800 board with me to test it and will require your help to do so. --- From: Sourav Poddar sourav.pod...@ti.com Date: Wed, 1 Aug 2012 15:44:12 +0530 Subject: [RFT/PATCH] serial: omap: Fix N800 serial init issue. This patch might solve the N800 serial init issue. This patch will also give pointers if there is any mux settings issue with N800 OR a mismatch between the initial harware state, runtime PM state and omap hwmod state. I don't have a N800 schematics to check about the mux settings getting used. The observation on beagle board XM with this patch on different boards looks flaky, so your feedback on beagle board will also be very helpful. Cc: Felipe Balbi ba...@ti.com Signed-off-by: Sourav Poddar sourav.pod...@ti.com --- drivers/tty/serial/omap-serial.c |1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. Kevin pm_runtime_enable(pdev-dev); pm_runtime_use_autosuspend(pdev-dev); pm_runtime_set_autosuspend_delay(pdev-dev, -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. As such, it seems this issue isn't making any progress as we had already established that merely doing a pm_runtime_set_active() before pm_runtime_enable() was going to break other platforms. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi Russell, From: Russell King - ARM Linux [li...@arm.linux.org.uk] Sent: Friday, October 12, 2012 10:12 PM To: Kevin Hilman Cc: Poddar, Sourav; Paul Walmsley; Balbi, Felipe; gre...@linuxfoundation.org; t...@atomide.com; linux-ker...@vger.kernel.org; Shilimkar, Santosh; linux-ser...@vger.kernel.org; linux-omap@vger.kernel.org; linux-arm-ker...@lists.infradead.org; a...@linux.intel.com Subject: Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended. On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. Sorry for the late reply on this. I tried this sequence and it worked perfectly fine on panda and beagle. As such, it seems this issue isn't making any progress as we had already established that merely doing a pm_runtime_set_active() before pm_runtime_enable() was going to break other platforms. I was trying to analyse your explanations on this and since omap_device_enable is not generally recommended, I was trying to see if anything else can be done to get around this. I send this patch for N800 testing so as to see how it behaves. (We are suspecting that there might be mux setting issue also with N800). ~Sourav -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Russell King - ARM Linux li...@arm.linux.org.uk writes: On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. Yes, that solution would work (though I didn't actually try it.) However, we can't use omap_device_enable() in the driver. We're trying to clean all the drivers of OMAP-specific APIs. That being said, something similar could be done in the device/board init code to ensure the UART HW is in the state that the driver is expecting it, but again, that would just mask the real problem which is that a (re)init of the console UART on 2420/n800 is causing output to disappear. As I detailed in an earlier response, I still think it's the fact that the pinmux is not setup correctly for the console UART pins in the board file, so when the UART is initialized, its mux settings are changed from the bootloader defaults, causing output to disappear. As such, it seems this issue isn't making any progress as we had already established that merely doing a pm_runtime_set_active() before pm_runtime_enable() was going to break other platforms. Agreed. Kevin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Fri, Oct 12, 2012 at 05:29:55PM +, Poddar, Sourav wrote: Hi Russell, From: Russell King - ARM Linux [li...@arm.linux.org.uk] Sent: Friday, October 12, 2012 10:12 PM To: Kevin Hilman Cc: Poddar, Sourav; Paul Walmsley; Balbi, Felipe; gre...@linuxfoundation.org; t...@atomide.com; linux-ker...@vger.kernel.org; Shilimkar, Santosh; linux-ser...@vger.kernel.org; linux-omap@vger.kernel.org; linux-arm-ker...@lists.infradead.org; a...@linux.intel.com Subject: Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended. On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. Sorry for the late reply on this. I tried this sequence and it worked perfectly fine on panda and beagle. As such, it seems this issue isn't making any progress as we had already established that merely doing a pm_runtime_set_active() before pm_runtime_enable() was going to break other platforms. I was trying to analyse your explanations on this and since omap_device_enable is not generally recommended, I was trying to see if anything else can be done to get around this. Right, so what you need is explanation about why I believe the above sequence to be necessary. What is happening is that we're starting from a device in unknown state. We don't know whether it is enabled or disabled. We don't know the state of the clocks or the power domain. PM runtime state is initialized at device creation in the device is suspended state. If we merely enable PM runtime from that state, we are telling the PM runtime subsystem that the device is _indeed_ suspended (disabled) at boot time. So, that causes the first pm_runtime_get() call to resume the device. Due to the OMAP runtime PM hooks at the bus layer, this causes _od_runtime_resume() to be called. _od_runtime_resume() does two things. It calls omap_device_enable() to ensure that the device is woken up (such as, ensuring that the power domain is on, and turning on the clocks etc.) It then goes on to call the device PM layers to call the driver specific runtime PM resume hook. So, in summary, what this sequence does is: pm_runtime_enable(pdev-dev); pm_runtime_use_autosuspend(pdev-dev); pm_runtime_set_autosuspend_delay(pdev-dev, omap_up_info-autosuspend_timeout); pm_runtime_irq_safe(pdev-dev); pm_runtime_get_sync(pdev-dev); is, at the last call, it calls: _od_runtime_resume() omap_device_enable() serial_omap_runtime_resume() Your original patch at the head of this thread says that the driver specific runtime resume call causes a problem for N800 - because the device is already enabled and setup. Okay, so the initial device state does not match the runtime PM state. So, what happens if we _do_ make it match your state - as required by the runtime PM documentation - by adding a call before the sequence: pm_runtime_set_active(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_use_autosuspend(pdev-dev); pm_runtime_set_autosuspend_delay(pdev-dev, omap_up_info-autosuspend_timeout); pm_runtime_irq_safe(pdev-dev); pm_runtime_get_sync(pdev-dev); Right, now runtime PM knows that the device is enabled and alive prior to that pm_runtime_get_sync() call, and it will _not_ call the runtime resume hooks. However, this breaks beaglebone, because the device is disabled when this driver probes. So, we have exactly the opposite problem here - the device is disabled, but runtime PM thinks it is enabled. The _two_ problems are precisely the same problem: the runtime PM state does not accurately reflect the actual hardware state - again, as required by the runtime PM documentation. The only sane solution to this is to ensure that the hardware _is_ in a known state prior to enabling runtime PM. How do we do that? Well, the clue
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Fri, Oct 12, 2012 at 10:59:22AM -0700, Kevin Hilman wrote: Russell King - ARM Linux li...@arm.linux.org.uk writes: On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. Yes, that solution would work (though I didn't actually try it.) However, we can't use omap_device_enable() in the driver. We're trying to clean all the drivers of OMAP-specific APIs. That being said, something similar could be done in the device/board init code to ensure the UART HW is in the state that the driver is expecting it, but again, that would just mask the real problem which is that a (re)init of the console UART on 2420/n800 is causing output to disappear. See my more expansive suggestion just posted. Whatever way, this discrepancy between runtime PM state and actual device state is what is biting you, and it is that which needs fixing. It's fairly easy to fix given the right design, one which several other bus types are already using. Given the route that OMAP went down when adopting runtime PM, it's going to be a big change across many drivers, because there's no way to gradually transition them, but that's unfortunately one of the results of ignoring requirements of the layers being used. Sooner or later the oversights come back to haunt. Just make sure it's not the ghost of Jaws. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Russell King - ARM Linux li...@arm.linux.org.uk writes: On Fri, Oct 12, 2012 at 10:59:22AM -0700, Kevin Hilman wrote: Russell King - ARM Linux li...@arm.linux.org.uk writes: On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote: Sourav sourav.pod...@ti.com writes: diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6ede6fd..3fbc7f7 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct platform_device *pdev) INIT_WORK(up-qos_work, serial_omap_uart_qos_work); platform_set_drvdata(pdev, up); + pm_runtime_set_active(pdev-dev); NAK. This will obviously break platforms where the UARTs are not active before driver loads. I thought I had proposed a solution for this issue, which was this sequence: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); Yes, I can understand people not liking the omap_device_enable() there, but I also notice that the email suggesting that never got a reply either - not even a I tried this and it doesn't work or it does work. Yes, that solution would work (though I didn't actually try it.) However, we can't use omap_device_enable() in the driver. We're trying to clean all the drivers of OMAP-specific APIs. That being said, something similar could be done in the device/board init code to ensure the UART HW is in the state that the driver is expecting it, but again, that would just mask the real problem which is that a (re)init of the console UART on 2420/n800 is causing output to disappear. See my more expansive suggestion just posted. Whatever way, this discrepancy between runtime PM state and actual device state is what is biting you, and it is that which needs fixing. I'm not conviced (yet) that a mismatch is the root cause. Yes, that's what the author of $SUBJECT patch assumed and stated, but I'm not pursuaded. If it's an improperly configured mux issue, then the UART will break whenever the device is actually omap_device_enable'd, whether in the driver or in the bus layer. Kevin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
* Kevin Hilman khil...@deeprootsystems.com [121012 13:34]: I'm not conviced (yet) that a mismatch is the root cause. Yes, that's what the author of $SUBJECT patch assumed and stated, but I'm not pursuaded. If it's an improperly configured mux issue, then the UART will break whenever the device is actually omap_device_enable'd, whether in the driver or in the bus layer. I tried booting n800 here with CONFIG_OMAP_MUX disabled, and no change. Serial console output stops right when the console initializes. Regards, Tony -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi Sourav, Felipe, any progress on fixing the N800 problem? Would be good to keep it booting since we use it as our primary 2420 test platform. - Paul -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Poddar, Sourav sourav.pod...@ti.com writes: Hi, On Tue, Sep 25, 2012 at 2:51 PM, Russell King - ARM Linux li...@arm.linux.org.uk wrote: On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! The issue was observed at serial init itself in the N800 board and the log does not show up much. http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt What we thought the problem might be with n800 is that it tries to resume when it didn't suspend before. There are two ways through which we thought of handling this issue: a) set device as active before enabling pm (which will prevent pm_runtime_set_active(dev); pm_runtime_enable(dev); OR b) adding a suspended flag to struct omap_uart_port which gets set on suspend and cleared on resume. Then on resume you can check: if (!up-suspended) return 0; But using pm_runtime_set_active approach breaks things even on beagle board xm, though it works fine on Panda. Therefore, we used the suspended flag approach. So. I just wanted to get some feedback from community about how using pm_runtime_set_active behaves differently in omap3 and omap4. As Russell has already pointed out in great detail, the difference is simply a mismatch between assumed HW stated and actual hardware state between various boards. Put simply, the driver assumes the HW is disabled (runtime suspended) when it loads, and the first runtime resume is meant to enable the HW. If that assumption is wrong, it needs to be fixed. Have you figured out why the HW is already active on OMAP2? (probably bootloader?) That being said, already active HW should not cause this problem. In fact, because of possible early console use, the hwmod init of the UART hwmods does not idle/reset them on boot, so they are left in the state that the bootloader set them in. When the hwmod is later enabled for real during probe, the hwmod muxing is done for that IP. So, I suspect what is really happening is that the mux settings are not right for the UARTS on n800, so when the probe happens, the UART mux settings are changed and you lose the UART. Can you double check the UART mux settings for that board? You might need some different mux settings in the board file. Kevin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 01:52:03PM +0530, Poddar, Sourav wrote: Hi Greg, Ping on this? It was a RFT patch, with a huge thread. What's the resolution here? Did people figure out the real problem here or not? If so, care to resend the proper patch so I know what to apply? thanks, greg k-h -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi Greg,
Ping on this?
On Tue, Sep 18, 2012 at 6:10 PM, Sourav Poddar sourav.pod...@ti.com wrote:
Greg's tty-next is not booting on 2420 based N800. The failure is
observed at serial init itself. The reason might be that n800 tries to
resume even though it is not suspended before.
Reported-by: Paul Walmsley p...@pwsan.com
Signed-off-by: Sourav Poddar sourav.pod...@ti.com
---
This patch is developed on top of greg's tty-next branch
CommitId: e740d8f tty: serial: Samsung: Fix return value +
the following patch which I have already posted to the mailing list.
http://comments.gmane.org/gmane.linux.ports.arm.omap/84729
drivers/tty/serial/omap-serial.c | 11 ++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/omap-serial.c
b/drivers/tty/serial/omap-serial.c
index 3c05c5e..bc355f2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -110,6 +110,7 @@ struct uart_omap_port {
u32 calc_latency;
struct work_struct qos_work;
struct pinctrl *pins;
+ unsigned intsuspended:1;
};
#define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port,
port)))
@@ -1545,14 +1546,20 @@ static int serial_omap_runtime_suspend(struct device
*dev)
up-latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
schedule_work(up-qos_work);
+ up-suspended = true;
+
return 0;
}
static int serial_omap_runtime_resume(struct device *dev)
{
struct uart_omap_port *up = dev_get_drvdata(dev);
+ u32 loss_cnt;
+
+ if (!up-suspended)
+ return 0;
- u32 loss_cnt = serial_omap_get_context_loss_count(up);
+ loss_cnt = serial_omap_get_context_loss_count(up);
if (up-context_loss_cnt != loss_cnt)
serial_omap_restore_context(up);
@@ -1560,6 +1567,8 @@ static int serial_omap_runtime_resume(struct device
*dev)
up-latency = up-calc_latency;
schedule_work(up-qos_work);
+ up-suspended = false;
+
return 0;
}
#endif
--
1.7.1
~Sourav
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Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 01:52:03PM +0530, Poddar, Sourav wrote: Hi Greg, Ping on this? On Tue, Sep 18, 2012 at 6:10 PM, Sourav Poddar sourav.pod...@ti.com wrote: Greg's tty-next is not booting on 2420 based N800. The failure is observed at serial init itself. The reason might be that n800 tries to resume even though it is not suspended before. How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 01:52:03PM +0530, Poddar, Sourav wrote: Hi Greg, Ping on this? On Tue, Sep 18, 2012 at 6:10 PM, Sourav Poddar sourav.pod...@ti.com wrote: Greg's tty-next is not booting on 2420 based N800. The failure is observed at serial init itself. The reason might be that n800 tries to resume even though it is not suspended before. How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? -- balbi signature.asc Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? Also, if you look into chapter 9 of the runtime_pm documentation, starting on line 822 you'll see documentation suggests the use of mystruct-is_suspended flag. -- balbi signature.asc Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi, On Tue, Sep 25, 2012 at 10:21:18AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! why are you always so over the top like that ? This is just counter-productive to say the least. What I'm trying to say here, is that there might be a bug either on pm core or on OMAP3's implementation and I'd like to get input from Tony, Santosh, Paul, etc before going forward. Maybe it's something they've already been through, or maybe it rings a bell and points to somewhere we should look for. anyway, instead of feeding your ego, we can stop this discussion and let Sourav see what he can come up with. -- balbi signature.asc Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi, On Tue, Sep 25, 2012 at 2:51 PM, Russell King - ARM Linux li...@arm.linux.org.uk wrote: On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! The issue was observed at serial init itself in the N800 board and the log does not show up much. http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt What we thought the problem might be with n800 is that it tries to resume when it didn't suspend before. There are two ways through which we thought of handling this issue: a) set device as active before enabling pm (which will prevent pm_runtime_set_active(dev); pm_runtime_enable(dev); OR b) adding a suspended flag to struct omap_uart_port which gets set on suspend and cleared on resume. Then on resume you can check: if (!up-suspended) return 0; But using pm_runtime_set_active approach breaks things even on beagle board xm, though it works fine on Panda. Therefore, we used the suspended flag approach. So. I just wanted to get some feedback from community about how using pm_runtime_set_active behaves differently in omap3 and omap4. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 12:48:16PM +0300, Felipe Balbi wrote: Hi, On Tue, Sep 25, 2012 at 10:21:18AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! why are you always so over the top like that ? This is just counter-productive to say the least. Because you are accusing me of potentially breaking your beagleboard for merely suggesting further investigation and a better commit message. You are the one going over the top, not me. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 11:29:58AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 12:48:16PM +0300, Felipe Balbi wrote: Hi, On Tue, Sep 25, 2012 at 10:21:18AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote: How is this happening? I think that needs proper investigation - or if it's had more investigation, then the results needs to be included in the commit description so that everyone can understand the issue here. We should not be resuming a device which hasn't been suspended. Maybe the runtime PM enable sequence is wrong, and that's what should be fixed instead? This sequence in the probe() function: pm_runtime_irq_safe(pdev-dev); pm_runtime_enable(pdev-dev); pm_runtime_get_sync(pdev-dev); would enable runtime PM while the s/w state indicates that it's disabled, and then that pm_runtime_get_sync() will want to resume the device. See the section 5. Runtime PM Initialization, Device Probing and Removal in Documentation/power/runtime_pm.txt, specifically the second paragraph of that section. that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... In any case, pm_runtime_get_sync() in probe will always call runtime_resume callback, right ? Well, if the runtime PM state says it's suspended, and then you enable runtime PM, the first call to pm_runtime_get_sync() will trigger a resume attempt. The patch description is complaining about resume events without there being a preceding suspend event. This could well be why. that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? What would cause a regression on beagleboard XM? I have not suggested any change other than more investigation of the issue and a fuller patch description - yet you're screaming (idiotically IMHO) that mere investigation would break beagleboard. Well, if it's _that_ fragile, that mere investigation of this issue by someone elsewhere on the planet would break your beagleboard, maybe it deserves to be broken! why are you always so over the top like that ? This is just counter-productive to say the least. Because you are accusing me of potentially breaking your beagleboard for merely suggesting further investigation and a better commit message. Where did I accuse you of anyting ? I just mentioned we experienced a regression with beagleboard XM when using pm_runtime_set_active(). here's my quote: that was tested. It worked in pandaboard but didn't work on beagleboard XM. Sourav tried to start a discussion about that, but it simply died... To add extra info, here you go: We pinged Paul and asked if he had seen that before, he had no pointers... Because Documentation/power/runtime_pm.txt was using a mystruct-is_suspended flag, we just decided to follow the same design since no-one was able to suggest why pm_runtime_set_active() was breaking beagleXM nor how it was supposed to actually work. Reading the code: pm_runtime_set_active() would tell pm_runtime core the device is actually active by setting runtime_status to RPM_ACTIVE, thus the following pm_runtime_get_sync() wouldn't actually call runtime_resume() callback, but it would increment usage_counter. I can't see why this would fail on beagleXM, but it does and we'd like to hear in which situations this could fail... -- balbi signature.asc Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Right, let's get this thread back onto a constructive footing and try to understand the problems here. On Tue, Sep 25, 2012 at 03:26:06PM +0530, Poddar, Sourav wrote: The issue was observed at serial init itself in the N800 board and the log does not show up much. http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt Right, so output stops when ttyO2 is initialized. What we thought the problem might be with n800 is that it tries to resume when it didn't suspend before. There are two ways through which we thought of handling this issue: a) set device as active before enabling pm (which will prevent pm_runtime_set_active(dev); pm_runtime_enable(dev); OR b) adding a suspended flag to struct omap_uart_port which gets set on suspend and cleared on resume. Then on resume you can check: if (!up-suspended) return 0; But using pm_runtime_set_active approach breaks things even on beagle board xm, though it works fine on Panda. Right, so now the question becomes - what is different on the Beagle Board that prevents solution (a) from working - or put it another way, have we uncovered _another_ bug. For N800, for ttyO0 and ttyO1 which aren't in use, it may be correct. We don't know for certain. For ttyO2, the port is clearly already in use as it's being used for console output. So that means it's _not_ in suspended state, and therefore the initial runtime PM state is wrong. For Beagleboard - who knows, we have no information on that. All we know is that your (a) sequence causes a regression. Anyway, let's analyse the code paths. What is pm_runtime_get_sync() doing? Well, it calls __pm_runtime_resume(, RPM_GET_PUT). That alters the parent device's state (which doesn't matter for this, as the platform device is a child of the main platform device, which has no runtime PM.) It then calls the resume callback (from the pm domain/type/class/bus/ driver) and then does an idle check. OMAP devices have a pm domain, so this is the candidate for the callback at this level, which gets us into _od_runtime_resume(). This calls omap_device_enable() before then moving on to the driver's runtime resume method, and at that point the runtime PM resume is complete. So, with your (a) solution, what's different is that we omit calling omap_device_enable(). Therefore, my hunch is the reason that Beagleboard doesn't work is because it doesn't like missing that call. I bet if you do this: omap_device_enable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); that this will solve your problem, and Beagleboard will continue working. What we have is a mismatch in both your case, and the Beagleboard case, between the real state of the hardware, the runtime PM state, and the OMAP hwmod state, and the above should bring all those states entirely into line with each other for _every_ case. It doesn't need any hacks to prevent resume callbacks without prior suspends (which, incidentally, the runtime PM core already guarantees provided you get the initial state correct.) -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 01:37:03PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 11:29:58AM +0100, Russell King - ARM Linux wrote: Because you are accusing me of potentially breaking your beagleboard for merely suggesting further investigation and a better commit message. Where did I accuse you of anyting ? I just mentioned we experienced a regression with beagleboard XM when using pm_runtime_set_active(). I quote: : But should we cause a regression to beagleboard XM because of that ? I say again: I was _only_ suggesting further investigation, yet you were mouthing off about causing a regression to beagleboard because of that, effectively saying that no, we should not do any further investigation and this is the only fix. To add extra info, here you go: Finally, something constructive. We pinged Paul and asked if he had seen that before, he had no pointers... Because Documentation/power/runtime_pm.txt was using a mystruct-is_suspended flag, we just decided to follow the same design since no-one was able to suggest why pm_runtime_set_active() was breaking beagleXM nor how it was supposed to actually work. Reading the code: pm_runtime_set_active() would tell pm_runtime core the device is actually active by setting runtime_status to RPM_ACTIVE, thus the following pm_runtime_get_sync() wouldn't actually call runtime_resume() callback, but it would increment usage_counter. I can't see why this would fail on beagleXM, but it does and we'd like to hear in which situations this could fail... Well, I've just spent five minutes analysing the code paths - which I hadn't looked at before - and I've pointed out what's probably causing the problem for Beagle. I think you owe me an appology over your aggressive attitude towards my suggestions that there needed to be some further investigation. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote: that's most likely, of course. But should we cause a regression to beagleboard XM because of that ? Also, if you look into chapter 9 of the runtime_pm documentation, starting on line 822 you'll see documentation suggests the use of mystruct-is_suspended flag. BTW, I'll point out a fatal flaw in your justification above. If you read the entire example, you'll see that the is_suspended flag is _not_ used to prevent resumes without suspends, but is used as a flag to control whether the driver processes requests or not. That's entirely functionally different from using a is_suspended flag in the way you mention above. Section 5 is quite clear about the requirements at initialization time for runtime PM, and nothing in section 9 contradicts that, and the is_suspended flag in that example has nothing to do with any of this. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Hi, On Tue, Sep 25, 2012 at 12:07:03PM +0100, Russell King - ARM Linux wrote: On Tue, Sep 25, 2012 at 01:37:03PM +0300, Felipe Balbi wrote: On Tue, Sep 25, 2012 at 11:29:58AM +0100, Russell King - ARM Linux wrote: Because you are accusing me of potentially breaking your beagleboard for merely suggesting further investigation and a better commit message. Where did I accuse you of anyting ? I just mentioned we experienced a regression with beagleboard XM when using pm_runtime_set_active(). I quote: : But should we cause a regression to beagleboard XM because of that ? maybe that wasn't the best way to put it, but I was trying to point out that either there was a bug on pm core or omap_device/hwmod, not that we shouldn't investigate. I say again: I was _only_ suggesting further investigation, yet you were mouthing off about causing a regression to beagleboard because of that, effectively saying that no, we should not do any further investigation and this is the only fix. not what I meant, but fair enough... The because of that was supposed to mean because of pm_runtime_set_active(). I find the documentation for that particular call to be rather poor and a bit confusing, specially when further down, the very same document uses a is_suspended flag which, in fact, shouldn't be needed when we have pm_runtime_is_suspended() and the like. We pinged Paul and asked if he had seen that before, he had no pointers... Because Documentation/power/runtime_pm.txt was using a mystruct-is_suspended flag, we just decided to follow the same design since no-one was able to suggest why pm_runtime_set_active() was breaking beagleXM nor how it was supposed to actually work. Reading the code: pm_runtime_set_active() would tell pm_runtime core the device is actually active by setting runtime_status to RPM_ACTIVE, thus the following pm_runtime_get_sync() wouldn't actually call runtime_resume() callback, but it would increment usage_counter. I can't see why this would fail on beagleXM, but it does and we'd like to hear in which situations this could fail... Well, I've just spent five minutes analysing the code paths - which I hadn't looked at before - and I've pointed out what's probably causing the problem for Beagle. I think you owe me an appology over your aggressive attitude towards my suggestions that there needed to be some further investigation. I don't see any aggressive attitude towards what you suggested, actually. Mailing list archives are available to check, but the one cursing around was always yourself and THAT deserves an apology. If you still think I've been at all aggressive, then sure, I apologize, it wasn't what I meant though. -- balbi signature.asc Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 25, 2012 at 02:12:43PM +0300, Felipe Balbi wrote: I don't see any aggressive attitude towards what you suggested, actually. Mailing list archives are available to check, but the one cursing around was always yourself and THAT deserves an apology. Total rubbish. No apology, because I wasn't cursing you. Whatever, I'm not going to re-explain the email thread. What I said was that your raising of beagleboard breakage (twice) was idiotic to a request for investigation. That's a statement I _still_ fully agree with, and I'll say it again if I have to. Trying to shut down investigation because investigation may break something _is_ idiotic - especially if the investigation reveals potential reasons why that breakage would occur. Further investigation is precisely how we arrive at better solutions. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On 19 September 2012 17:29, Felipe Balbi ba...@ti.com wrote: this is what I mean, actually. If we remove pm_runtime_get_sync() in exchange for pm_runtime_set_active() before pm_runtime_enable(), it works on PandaBoard, but breaks BeagleBoard. Perhaps it suggests that OMAP4 (PandaBoard) serial port is already activated but OMAP3 (BeagleBoard) isn't. So we need to reflect that either by doing pm_runtime_set_active() only on OMAP4 or by bringing up the OMAP3 too before the pm_runtime_set_active() call. BTW I understand get_sync(), set_active() and enable() are for different purposes, they can't be traded for one another. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 18, 2012 at 5:02 PM, Felipe Balbi ba...@ti.com wrote: On Tue, Sep 18, 2012 at 06:10:50PM +0530, Sourav Poddar wrote: Greg's tty-next is not booting on 2420 based N800. The failure is observed at serial init itself. The reason might be that n800 tries to resume even though it is not suspended before. Reported-by: Paul Walmsley p...@pwsan.com Signed-off-by: Sourav Poddar sourav.pod...@ti.com FWIW: Reviewed-by: Felipe Balbi ba...@ti.com Paul does this fix the issue for you ? Note that it depends on a previous patch Sourav sent [1] [1] http://marc.info/?l=linux-omapm=134796819607889w=2 There's one thing that gets my attention, though, why only n800 would fail here ? I wonder if we should be using: pm_runtime_set_active(dev); pm_runtime_get_enable(dev); to prevent our runtime_resume() to be called from probe, but Sourav tested and it doesn't work on BeagleBoard, but it works on PandaBoard. Does it ring any bell ?? Well I guess it's normal resume callback is called during probe as pm_runtime_get_sync() is called there, and according to documentation [1], devices are assumed to be suspended before probe is called. According to [1], pm_runtime_set_active() should be called before pm_runtime_enable() to indicate to the core that device is active during probe if that's the case, I guess this means pm_runtime_get_sync() is not needed in that case, but I'm not sure what's the actual serial state during probe nowadays. [1] chapter 5 of Documentation/power/runtime_pm.txt: The initial runtime PM status of all devices is 'suspended', but it need not reflect the actual physical state of the device. Thus, if the device is initially active (i.e. it is able to process I/O), its runtime PM status must be changed to 'active', with the help of pm_runtime_set_active(), before pm_runtime_enable() is called for the device. -- GraÅžvydas -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[RFT/PATCH] serial: omap: prevent resume if device is not suspended.
Greg's tty-next is not booting on 2420 based N800. The failure is
observed at serial init itself. The reason might be that n800 tries to
resume even though it is not suspended before.
Reported-by: Paul Walmsley p...@pwsan.com
Signed-off-by: Sourav Poddar sourav.pod...@ti.com
---
This patch is developed on top of greg's tty-next branch
CommitId: e740d8f tty: serial: Samsung: Fix return value +
the following patch which I have already posted to the mailing list.
http://comments.gmane.org/gmane.linux.ports.arm.omap/84729
drivers/tty/serial/omap-serial.c | 11 ++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 3c05c5e..bc355f2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -110,6 +110,7 @@ struct uart_omap_port {
u32 calc_latency;
struct work_struct qos_work;
struct pinctrl *pins;
+ unsigned intsuspended:1;
};
#define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port,
port)))
@@ -1545,14 +1546,20 @@ static int serial_omap_runtime_suspend(struct device
*dev)
up-latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
schedule_work(up-qos_work);
+ up-suspended = true;
+
return 0;
}
static int serial_omap_runtime_resume(struct device *dev)
{
struct uart_omap_port *up = dev_get_drvdata(dev);
+ u32 loss_cnt;
+
+ if (!up-suspended)
+ return 0;
- u32 loss_cnt = serial_omap_get_context_loss_count(up);
+ loss_cnt = serial_omap_get_context_loss_count(up);
if (up-context_loss_cnt != loss_cnt)
serial_omap_restore_context(up);
@@ -1560,6 +1567,8 @@ static int serial_omap_runtime_resume(struct device *dev)
up-latency = up-calc_latency;
schedule_work(up-qos_work);
+ up-suspended = false;
+
return 0;
}
#endif
--
1.7.1
--
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Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, Sep 18, 2012 at 06:10:50PM +0530, Sourav Poddar wrote:
Greg's tty-next is not booting on 2420 based N800. The failure is
observed at serial init itself. The reason might be that n800 tries to
resume even though it is not suspended before.
Reported-by: Paul Walmsley p...@pwsan.com
Signed-off-by: Sourav Poddar sourav.pod...@ti.com
FWIW:
Reviewed-by: Felipe Balbi ba...@ti.com
Paul does this fix the issue for you ? Note that it depends on a
previous patch Sourav sent [1]
[1] http://marc.info/?l=linux-omapm=134796819607889w=2
There's one thing that gets my attention, though, why only n800 would
fail here ?
I wonder if we should be using:
pm_runtime_set_active(dev);
pm_runtime_get_enable(dev);
to prevent our runtime_resume() to be called from probe, but Sourav
tested and it doesn't work on BeagleBoard, but it works on PandaBoard.
Does it ring any bell ??
---
This patch is developed on top of greg's tty-next branch
CommitId: e740d8f tty: serial: Samsung: Fix return value +
the following patch which I have already posted to the mailing list.
http://comments.gmane.org/gmane.linux.ports.arm.omap/84729
drivers/tty/serial/omap-serial.c | 11 ++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/omap-serial.c
b/drivers/tty/serial/omap-serial.c
index 3c05c5e..bc355f2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -110,6 +110,7 @@ struct uart_omap_port {
u32 calc_latency;
struct work_struct qos_work;
struct pinctrl *pins;
+ unsigned intsuspended:1;
};
#define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port,
port)))
@@ -1545,14 +1546,20 @@ static int serial_omap_runtime_suspend(struct device
*dev)
up-latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
schedule_work(up-qos_work);
+ up-suspended = true;
+
return 0;
}
static int serial_omap_runtime_resume(struct device *dev)
{
struct uart_omap_port *up = dev_get_drvdata(dev);
+ u32 loss_cnt;
+
+ if (!up-suspended)
+ return 0;
- u32 loss_cnt = serial_omap_get_context_loss_count(up);
+ loss_cnt = serial_omap_get_context_loss_count(up);
if (up-context_loss_cnt != loss_cnt)
serial_omap_restore_context(up);
@@ -1560,6 +1567,8 @@ static int serial_omap_runtime_resume(struct device
*dev)
up-latency = up-calc_latency;
schedule_work(up-qos_work);
+ up-suspended = false;
+
return 0;
}
#endif
--
1.7.1
--
balbi
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Description: Digital signature
Re: [RFT/PATCH] serial: omap: prevent resume if device is not suspended.
On Tue, 18 Sep 2012, Felipe Balbi wrote: On Tue, Sep 18, 2012 at 06:10:50PM +0530, Sourav Poddar wrote: Greg's tty-next is not booting on 2420 based N800. The failure is observed at serial init itself. The reason might be that n800 tries to resume even though it is not suspended before. Reported-by: Paul Walmsley p...@pwsan.com Signed-off-by: Sourav Poddar sourav.pod...@ti.com FWIW: Reviewed-by: Felipe Balbi ba...@ti.com Paul does this fix the issue for you ? Note that it depends on a previous patch Sourav sent [1] [1] http://marc.info/?l=linux-omapm=134796819607889w=2 Yes, thanks - that fixes it, Tested-by: Paul Walmsley p...@pwsan.com There's one thing that gets my attention, though, why only n800 would fail here ? I wonder if we should be using: pm_runtime_set_active(dev); pm_runtime_get_enable(dev); to prevent our runtime_resume() to be called from probe, but Sourav tested and it doesn't work on BeagleBoard, but it works on PandaBoard. Does it ring any bell ?? Nothing off the top of my head but haven't looked into it -- maybe this rings a bell with Kevin? - Paul -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
