Hello Rafael,
On Fri, Nov 15, 2024 at 09:58:31PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> If the :enter_dead() idle state callback fails for a certain state,
> there may be still a shallower state for which it will work.
>
> Because the only caller of cpuidle_play_dead(), native_play_dead(),
> falls back to hlt_play_dead() if it returns an error, it should
> better try all of the idle states for which :enter_dead() is present
> before failing, so change it accordingly.
>
> Also notice that the :enter_dead() state callback is not expected
> to return on success (the CPU should be "dead" then), so make
> cpuidle_play_dead() ignore its return value.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Tested-by: Mario Limonciello <mario.limonciello@xxxxxxx> # 6.12-rc7
Thanks for fixing this.
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
--
Thanks and Regards
gautham.
> ---
>
> v1 -> v2:
> * Make cpuidle_play_dead() never return 0.
> * Add tags from Mario (I have added them because the change of the patch
> should not make a practical difference, but if you want them to be
> dropped, please let me know).
>
> ---
> drivers/cpuidle/cpuidle.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> Index: linux-pm/drivers/cpuidle/cpuidle.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/cpuidle.c
> +++ linux-pm/drivers/cpuidle/cpuidle.c
> @@ -69,11 +69,15 @@ int cpuidle_play_dead(void)
> if (!drv)
> return -ENODEV;
>
> - /* Find lowest-power state that supports long-term idle */
> - for (i = drv->state_count - 1; i >= 0; i--)
> + for (i = drv->state_count - 1; i >= 0; i--) {
> if (drv->states[i].enter_dead)
> - return drv->states[i].enter_dead(dev, i);
> + drv->states[i].enter_dead(dev, i);
> + }
>
> + /*
> + * If :enter_dead() is successful, it will never return, so reaching
> + * here means that all of them failed above or were not present.
> + */
> return -ENODEV;
> }
>
>
>
>
