Re: [[PATCH]] Revert "leds: handle suspend/resume in heartbeat trigger"

Geert Uytterhoeven
2017-08-25T08:23:13Z

On Wed, Aug 23, 2017 at 9:34 PM, Pavel Machek <pavel@ucw.cz> wrote:
>> On Tue, Jun 13, 2017 at 4:39 AM, Zhang Bo <bo.zhang@nxp.com> wrote:
>> > This reverts commit 5ab92a7cb82c66bf30685583a38a18538e3807db.
>> >
>> > System cannot enter suspend mode because of heartbeat led trigger.
>> > In autosleep_wq, try_to_suspend function will try to enter suspend
>> > mode in specific period. it will get wakeup_count then call pm_notifier
>> > chain callback function and freeze processes.
>> > Heartbeat_pm_notifier is called and it call led_trigger_unregister to
>> > change the trigger of led device to none. It will send uevent message
>> > and the wakeup source count changed. As wakeup_count changed, suspend
>> > will abort.
>> >
>> > Signed-off-by: Zhang Bo <bo.zhang@nxp.com>
>>
>> While investigating an heartbeat LED issue in v4.9.40-ltsi, I stumpled on this
>> revert (commit 436c4c45b5b9562b ("Revert "leds: handle suspend/resume in
>> heartbeat trigger"") in v4.12-rc6), which was not backported to v4.9 (yet).
>>
>> Interestingly, while running v4.9.x on r8a7791/koelsch with an LED configured
>> for heartbeat, I can actually suspend the system using s2ram.
>> However, after system resume the heartbeat LED no longer flashes.
>> /sys/class/leds/LED6/trigger shows the trigger is still "none", and thus
>> wasn't restored to "heartbeat" by the notifier.
>> There's no "could not re-register heartbeat trigger" message printed.
>>
>> Backporting the revert fixes this.
>
> You have my Acked-by: if you want to submit this to some -stable
> kernels...

Thank you!

Greg: Can you please queue 436c4c45b5b9562b ("Revert "leds: handle
suspend/resume in heartbeat trigger"") for v4.9.x or v4.9-ltsi?
Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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