Re: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
Hi Kevin, On Fri, Sep 14, 2012 at 2:15 AM, Kevin Hilman khil...@deeprootsystems.com wrote: From: Kevin Hilman khil...@ti.com On some platforms, bootloaders are known to do some interesting RTC programming. Without going into the obscurities as to why this may be the case, suffice it to say the the driver should not make any assumptions about the state of the RTC when the driver loads. In particular, the driver probe should be sure that all interrupts are disabled until otherwise programmed. This was discovered when finding bursty I2C traffic every second on Overo platforms. This I2C overhead was keeping the SoC from hitting deep power states. The cause was found to be the RTC firing every second on the I2C-connected TWL PMIC. Special thanks to Felipe Balbi for suggesting to look for a rogue driver as the source of the I2C traffic rather than the I2C driver itself. Special thanks to Steve Sakoman for helping track down the source of the continuous RTC interrups on the Overo boards. Tested that the continuous interrupt issue after doing a i2c mm on omap4sdp. This patch solves the issue. thanks, Cc: Felipe Balbi ba...@ti.com Cc: Steve Sakoman st...@sakoman.com Signed-off-by: Kevin Hilman khil...@ti.com --- Patch applies to v3.6-rc5 drivers/rtc/rtc-twl.c |5 + 1 file changed, 5 insertions(+) diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c index c5d06fe..9277d94 100644 --- a/drivers/rtc/rtc-twl.c +++ b/drivers/rtc/rtc-twl.c @@ -495,6 +495,11 @@ static int __devinit twl_rtc_probe(struct platform_device *pdev) if (ret 0) goto out1; + /* ensure interrupts are disabled, bootloaders can be strange */ + ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG); + if (ret 0) + dev_warn(pdev-dev, unable to disable interrupt\n); + Now that it is always 0 can the below read be removed as it is redundant now. /* init cached IRQ enable bits */ ret = twl_rtc_read_u8(rtc_irq_bits, REG_RTC_INTERRUPTS_REG); if (ret 0) -- 1.7.9.2 ___ linux-arm-kernel mailing list linux-arm-ker...@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- 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: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
Shubhrajyoti Datta omaplinuxker...@gmail.com writes: Hi Kevin, On Fri, Sep 14, 2012 at 2:15 AM, Kevin Hilman khil...@deeprootsystems.com wrote: From: Kevin Hilman khil...@ti.com On some platforms, bootloaders are known to do some interesting RTC programming. Without going into the obscurities as to why this may be the case, suffice it to say the the driver should not make any assumptions about the state of the RTC when the driver loads. In particular, the driver probe should be sure that all interrupts are disabled until otherwise programmed. This was discovered when finding bursty I2C traffic every second on Overo platforms. This I2C overhead was keeping the SoC from hitting deep power states. The cause was found to be the RTC firing every second on the I2C-connected TWL PMIC. Special thanks to Felipe Balbi for suggesting to look for a rogue driver as the source of the I2C traffic rather than the I2C driver itself. Special thanks to Steve Sakoman for helping track down the source of the continuous RTC interrups on the Overo boards. Tested that the continuous interrupt issue after doing a i2c mm on omap4sdp. This patch solves the issue. thanks, Cc: Felipe Balbi ba...@ti.com Cc: Steve Sakoman st...@sakoman.com Signed-off-by: Kevin Hilman khil...@ti.com --- Patch applies to v3.6-rc5 drivers/rtc/rtc-twl.c |5 + 1 file changed, 5 insertions(+) diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c index c5d06fe..9277d94 100644 --- a/drivers/rtc/rtc-twl.c +++ b/drivers/rtc/rtc-twl.c @@ -495,6 +495,11 @@ static int __devinit twl_rtc_probe(struct platform_device *pdev) if (ret 0) goto out1; + /* ensure interrupts are disabled, bootloaders can be strange */ + ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG); + if (ret 0) + dev_warn(pdev-dev, unable to disable interrupt\n); + Now that it is always 0 can the below read be removed as it is redundant now. Possibly, but I don't know this HW well enough to know if there are any persistent bits in that register on any of the various derivations of this PMIC. Since this read-back value is used throughout the driver, I decided not to mess with it when doing this targetted fix. 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: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
On Thu, Sep 13, 2012 at 1:45 PM, Kevin Hilman khil...@deeprootsystems.com wrote: From: Kevin Hilman khil...@ti.com On some platforms, bootloaders are known to do some interesting RTC programming. Without going into the obscurities as to why this may be the case, suffice it to say the the driver should not make any assumptions about the state of the RTC when the driver loads. In particular, the driver probe should be sure that all interrupts are disabled until otherwise programmed. This was discovered when finding bursty I2C traffic every second on Overo platforms. This I2C overhead was keeping the SoC from hitting deep power states. The cause was found to be the RTC firing every second on the I2C-connected TWL PMIC. Special thanks to Felipe Balbi for suggesting to look for a rogue driver as the source of the I2C traffic rather than the I2C driver itself. Special thanks to Steve Sakoman for helping track down the source of the continuous RTC interrups on the Overo boards. Cc: Felipe Balbi ba...@ti.com Cc: Steve Sakoman st...@sakoman.com Signed-off-by: Kevin Hilman khil...@ti.com Tested on Overo/Tobi, and I no longer see the 1/second interrupts. Also verified that alarm interrupts still work using rtcwake. Tested-by: Steve Sakoman st...@sakoman.com -- 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: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
On Fri, Sep 14, 2012 at 7:37 PM, Kevin Hilman khil...@deeprootsystems.com wrote: Shubhrajyoti Datta omaplinuxker...@gmail.com writes: Hi Kevin, On Fri, Sep 14, 2012 at 2:15 AM, Kevin Hilman khil...@deeprootsystems.com wrote: From: Kevin Hilman khil...@ti.com On some platforms, bootloaders are known to do some interesting RTC programming. Without going into the obscurities as to why this may be the case, suffice it to say the the driver should not make any assumptions about the state of the RTC when the driver loads. In particular, the driver probe should be sure that all interrupts are disabled until otherwise programmed. This was discovered when finding bursty I2C traffic every second on Overo platforms. This I2C overhead was keeping the SoC from hitting deep power states. The cause was found to be the RTC firing every second on the I2C-connected TWL PMIC. Special thanks to Felipe Balbi for suggesting to look for a rogue driver as the source of the I2C traffic rather than the I2C driver itself. Special thanks to Steve Sakoman for helping track down the source of the continuous RTC interrups on the Overo boards. Tested that the continuous interrupt issue after doing a i2c mm on omap4sdp. This patch solves the issue. thanks, Cc: Felipe Balbi ba...@ti.com Cc: Steve Sakoman st...@sakoman.com Signed-off-by: Kevin Hilman khil...@ti.com --- Patch applies to v3.6-rc5 drivers/rtc/rtc-twl.c |5 + 1 file changed, 5 insertions(+) diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c index c5d06fe..9277d94 100644 --- a/drivers/rtc/rtc-twl.c +++ b/drivers/rtc/rtc-twl.c @@ -495,6 +495,11 @@ static int __devinit twl_rtc_probe(struct platform_device *pdev) if (ret 0) goto out1; + /* ensure interrupts are disabled, bootloaders can be strange */ + ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG); + if (ret 0) + dev_warn(pdev-dev, unable to disable interrupt\n); + Now that it is always 0 can the below read be removed as it is redundant now. Possibly, but I don't know this HW well enough to know if there are any persistent bits in that register on any of the various derivations of this PMIC. Since this read-back value is used throughout the driver, I decided not to mess with it when doing this targetted fix. Indeed makes sense. 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: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
On Fri, 14 Sep 2012 08:33:42 -0700 Steve Sakoman st...@sakoman.com wrote: Tested-by: Steve Sakoman st...@sakoman.com Thanks. Given the tested-by's that are rolling in, I will assume that people are hitting this problem in 3.5 and perhaps earlier kernels, so I scheduled the fix for 3.6, with a -stable backport. I might have been wrong about that - in future, please do make these issues clear in the patch changelog? -- 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: [PATCH] RTC: TWL: ensure all interrupts are disabled during probe
On Fri, Sep 14, 2012 at 12:20 PM, Andrew Morton a...@linux-foundation.org wrote: Given the tested-by's that are rolling in, I will assume that people are hitting this problem in 3.5 and perhaps earlier kernels, so I scheduled the fix for 3.6, with a -stable backport. Yes, I just checked an Overo setup here that is running 3.2 and it has the same issue. So your plan for 3.6 and -stable is a good one. Steve -- 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
