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SubjectRe: [PATCH v2] thermal/core: Clear all mitigation when thermal zone is disabled
On Wed, Dec 29, 2021 at 8:03 AM Manaf Meethalavalappu Pallikunhi
<quic_manafm@quicinc.com> wrote:
>
> Whenever a thermal zone is in trip violated state, there is a chance
> that the same thermal zone mode can be disabled either via thermal
> core API or via thermal zone sysfs. Once it is disabled, the framework
> bails out any re-evaluation of thermal zone. It leads to a case where
> if it is already in mitigation state, it will stay the same state
> until it is re-enabled.

You seem to be arguing that disabling a thermal zone should prevent it
from throttling anything, which is reasonable, but I'm not sure if the
change below is sufficient for that.

> To avoid above mentioned issue, on thermal zone disable request
> reset thermal zone and clear mitigation for each trip explicitly.
>
> Signed-off-by: Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>
> ---
> drivers/thermal/thermal_core.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 51374f4..5f4e35b 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -427,6 +427,7 @@ static int thermal_zone_device_set_mode(struct thermal_zone_device *tz,
> enum thermal_device_mode mode)
> {
> int ret = 0;
> + int trip;

This can be declared in the block in which it is used.

>
> mutex_lock(&tz->lock);
>
> @@ -449,8 +450,14 @@ static int thermal_zone_device_set_mode(struct thermal_zone_device *tz,
>
> if (mode == THERMAL_DEVICE_ENABLED)

The coding style asks for braces here if they are used after the else.

> thermal_notify_tz_enable(tz->id);
> - else
> + else {
> + /* make sure all previous throttlings are cleared */
> + thermal_zone_device_init(tz);
> + for (trip = 0; trip < tz->trips; trip++)
> + handle_thermal_trip(tz, trip);

So I'm not sure if this makes the throttling go away in all cases (eg.
what if the current temperature is still above the given trip at this
point?).

> +
> thermal_notify_tz_disable(tz->id);
> + }
>
> return ret;
> }
>

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