Hi Zhang, On Tue, Jun 13, 2017 at 4:39 AM, Zhang Bo <bo.zhang@xxxxxxx> 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@xxxxxxx> 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. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds