[RFC PATCH 0/6] Suspend USB Host controller on bus suspend
Hi, This series attempts to suspend the OMAP EHCI host controller on USB Bus suspend. This will cause its parent, the OMAP USB Host Module as well as the USB TLL Module to be put in suspend and hence allow the USB power domain to be put in a lower power state. Then we no longer prevent the rest of the OMAP SoC from entering lower power states like RETention or OFF mode when USB (or system) is suspended. This was one of the main reason why EHCI_OMAP is still not enabled in OMAP2 defconfig. In order for remote wakeup or hub events (connect/disconnect) to be detected while in suspend, we need to rely on the IO daisy chaining mechanism on OMAP. This is nothing but configuring a pin to be wakeup capable and triggering an interrupt on any pin activity while the hardware module or the entire SoC is in sleep state. For this to work, we rely on the wakeup feature added to the omap-pinctrl-single driver in [1]. This takes care of routing IO pad wakeup interrupt to the right driver's interrupt handler (i.e. ehci_irq in our case). The pin state information for DEFAULT and IDLE is specified for the omap3beagle-xm board in patch 5. So this is tested only on omap3beagle-xm board. As the omap-ehci controller driver needs to do some additional work to put itself into suspend/resume and make sure it is resumed to process an interrupt, we need to be able to override irq, bus_suspend, and bus_resume handlers. This provision is done in patch 3. Patch 2 uses pinctrl framework to toggle USB host pins from DEFAULT state when active to IDLE state with wakeups enabled while in suspend. Patch 5 implements the suspend feature in ehci-omap driver and ensures that we don't loose events while in suspend. Please let me know what you think about it. I'm not 100% confident about tackling interrupt when the device is runtime suspended in patch 5. Please let me know if a race condition is possible here. [1] - OMAP pinctrl wakeup support http://thread.gmane.org/gmane.linux.ports.arm.omap/99010/focus=99041 cheers, -roger Roger Quadros (6): mfd: omap-usb-host: move initialization to module_init() mfd: omap-usb-host: Put pins in IDLE state on suspend USB: ehci: allow controller drivers to override irq & bus_suspend/resume USB: ehci-omap: Suspend the controller during bus suspend ARM: dts: omap3beagle-xm: Add idle state pins for USB host ARM: OMAP3: Enable Hardware Save and Restore for USB Host arch/arm/boot/dts/omap3-beagle-xm.dts | 29 -- arch/arm/mach-omap2/powerdomains3xxx_data.c |8 +-- drivers/mfd/omap-usb-host.c | 56 +++--- drivers/mfd/omap-usb-tll.c |8 +-- drivers/usb/host/ehci-hcd.c |9 +++- drivers/usb/host/ehci-hub.c |6 +- drivers/usb/host/ehci-omap.c| 82 +++ drivers/usb/host/ehci.h |6 ++ 8 files changed, 172 insertions(+), 32 deletions(-) -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC PATCH 0/6] Suspend USB Host controller on bus suspend
On Wed, 19 Jun 2013, Roger Quadros wrote: > Hi, > > This series attempts to suspend the OMAP EHCI host controller on USB > Bus suspend. Why do you want to suspend the host controller during bus suspend? They are two different operations and should be carried out at two different times. The controller should be suspended during controller suspend, not during bus suspend. > As the omap-ehci controller driver needs to do some additional work to put > itself into suspend/resume and make sure it is resumed to process an > interrupt, > we need to be able to override irq, bus_suspend, and bus_resume handlers. This > provision is done in patch 3. Do you still need to override these things if you do the controller suspend at the right time? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC PATCH 0/6] Suspend USB Host controller on bus suspend
On 06/19/2013 06:23 PM, Alan Stern wrote: > On Wed, 19 Jun 2013, Roger Quadros wrote: > >> Hi, >> >> This series attempts to suspend the OMAP EHCI host controller on USB >> Bus suspend. > > Why do you want to suspend the host controller during bus suspend? > They are two different operations and should be carried out at two > different times. The controller should be suspended during controller > suspend, not during bus suspend. > Good point. I didn't think it that way. I think it should work. >> As the omap-ehci controller driver needs to do some additional work to put >> itself into suspend/resume and make sure it is resumed to process an >> interrupt, >> we need to be able to override irq, bus_suspend, and bus_resume handlers. >> This >> provision is done in patch 3. > > Do you still need to override these things if you do the controller > suspend at the right time? > At least not for bus_suspend and bus_resume. We will still need to override the irq handler though. But, if we can take care of this generically in the ehci_irq handler (i.e. make sure controller is not suspended while accessing it) then we don't need such override for irq. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC PATCH 0/6] Suspend USB Host controller on bus suspend
On Thu, 20 Jun 2013, Roger Quadros wrote: > >> As the omap-ehci controller driver needs to do some additional work to put > >> itself into suspend/resume and make sure it is resumed to process an > >> interrupt, > >> we need to be able to override irq, bus_suspend, and bus_resume handlers. > >> This > >> provision is done in patch 3. > > > > Do you still need to override these things if you do the controller > > suspend at the right time? > > > > At least not for bus_suspend and bus_resume. We will still need to override > the irq > handler though. But, if we can take care of this generically in the ehci_irq > handler (i.e. make > sure controller is not suspended while accessing it) then we don't need such > override > for irq. I don't think you need to override anything. The high-level interrupt handler usb_hcd_irq() will avoid calling ehci_irq() when the HCD_HW_ACCESSIBLE flag isn't set. All you will need to do in ehci-omap.c is call synchronize_irq() after ehci_suspend() returns and before turning off the clocks. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
