Re: [PATCH v3] thermal: core: Add sanity checks for polling_delay and passive_delay

[Daniel Lezcano]

On 11/07/2024 14:39, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> If polling_delay is nonzero and passive_delay is greater than
> polling_delay, the thermal zone temperature will be updated less
> often when tz->passive is nonzero, which is not as expected.  Make
> the thermal zone registration fail with -EINVAL in that case as
> this is a clear thermal zone configuration mistake.
>
> If polling_delay is nonzero and passive_delay is 0, which is regarded
> as a valid thermal zone configuration, the thermal zone will use polling
> except when tz->passive is nonzero.  However, the expected behavior in
> that case is to continue temperature polling with the same delay value
> regardless of tz->passive, so set passive_delay to the polling_delay
> value then.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---

Reviewed-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>

> This supersedes
>
> https://lore.kernel.org/linux-pm/4940808.31r3eYUQgx@xxxxxxxxxxxxx/
>
> ---
>   drivers/thermal/thermal_core.c |    8 ++++++++
>   1 file changed, 8 insertions(+)
>
> Index: linux-pm/drivers/thermal/thermal_core.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_core.c
> +++ linux-pm/drivers/thermal/thermal_core.c
> @@ -1391,6 +1391,14 @@ thermal_zone_device_register_with_trips(
>   	if (num_trips > 0 && !trips)
>   		return ERR_PTR(-EINVAL);
>   
> +	if (polling_delay) {
> +		if (passive_delay > polling_delay)
> +			return ERR_PTR(-EINVAL);
> +
> +		if (!passive_delay)
> +			passive_delay = polling_delay;
> +	}
> +
>   	if (!thermal_class)
>   		return ERR_PTR(-ENODEV);
>   

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