Messages in this thread | | | Date | Tue, 20 Apr 2021 11:13:19 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCH] watchdog: qcom: Move suspend/resume to suspend_late/resume_early |
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Hi Guenter,
On 2021-03-11 01:53, Guenter Roeck wrote: > On Thu, Mar 11, 2021 at 01:50:04AM +0530, Sai Prakash Ranjan wrote: >> During suspend/resume usecases and tests, it is common to see issues >> such as lockups either in suspend path or resume path because of the >> bugs in the corresponding device driver pm handling code. In such >> cases, >> it is important that watchdog is active to make sure that we either >> receive a watchdog pretimeout notification or a bite causing reset >> instead of a hang causing us to hard reset the machine. >> >> There are good reasons as to why we need this because: >> >> * We can have a watchdog pretimeout governor set to panic in which >> case we can have a backtrace which would help identify the issue >> with the particular driver and cause a normal reboot. >> >> * Even in case where there is no pretimeout support, a watchdog >> bite is still useful because some firmware has debug support to dump >> CPU core context on watchdog bite for post-mortem analysis. >> >> * One more usecase which comes to mind is of warm reboot. In case we >> hard reset the target, a cold reboot could be induced resulting in >> lose of ddr contents thereby losing all the debug info. >> >> Currently, the watchdog pm callback just invokes the usual suspend >> and resume callback which do not have any special ordering in the >> sense that a watchdog can be suspended before the buggy device driver >> suspend callback and watchdog resume can happen after the buggy device >> driver resume callback. This would mean that the watchdog will not be >> active when the buggy driver cause the lockups thereby hanging the >> system. So to make sure this doesn't happen, move the watchdog pm to >> use late/early system pm callbacks which will ensure that the watchdog >> is suspended late and resumed early so that it can catch such issues. >> >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > > Reviewed-by: Guenter Roeck <linux@roeck-us.net> >
Gentle Ping. I don't see this in linux-next or linux-watchdog, please let me know if anything is pending from my side.
Thanks, Sai
>> --- >> drivers/watchdog/qcom-wdt.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c >> index e38a87ffe5f5..0d2209c5eaca 100644 >> --- a/drivers/watchdog/qcom-wdt.c >> +++ b/drivers/watchdog/qcom-wdt.c >> @@ -329,7 +329,9 @@ static int __maybe_unused qcom_wdt_resume(struct >> device *dev) >> return 0; >> } >> >> -static SIMPLE_DEV_PM_OPS(qcom_wdt_pm_ops, qcom_wdt_suspend, >> qcom_wdt_resume); >> +static const struct dev_pm_ops qcom_wdt_pm_ops = { >> + SET_LATE_SYSTEM_SLEEP_PM_OPS(qcom_wdt_suspend, qcom_wdt_resume) >> +}; >> >> static const struct of_device_id qcom_wdt_of_table[] = { >> { .compatible = "qcom,kpss-timer", .data = &match_data_apcs_tmr }, >> -- >> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a >> member >> of Code Aurora Forum, hosted by The Linux Foundation >>
-- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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