Re: [PATCH v3] thermal: core: Call monitor_thermal_zone() if zone temperature is invalid

[Eric Biggers <ebiggers@kernel.org>]

Hello,

On Thu, Jul 04, 2024 at 01:46:26PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Commit 202aa0d4bb53 ("thermal: core: Do not call handle_thermal_trip()
> if zone temperature is invalid") caused __thermal_zone_device_update()
> to return early if the current thermal zone temperature was invalid.
> 
> This was done to avoid running handle_thermal_trip() and governor
> callbacks in that case which led to confusion.  However, it went too
> far because monitor_thermal_zone() still needs to be called even when
> the zone temperature is invalid to ensure that it will be updated
> eventually in case thermal polling is enabled and the driver has no
> other means to notify the core of zone temperature changes (for example,
> it does not register an interrupt handler or ACPI notifier).
> 
> Also if the .set_trips() zone callback is expected to set up monitoring
> interrupts for a thermal zone, it needs to be provided with valid
> boundaries and that can only be done if the zone temperature is known.
> 
> Accordingly, to ensure that __thermal_zone_device_update() will
> run again after a failing zone temperature check, make it call
> monitor_thermal_zone() regardless of whether or not the zone
> temperature is valid and make the latter schedule a thermal zone
> temperature update if the zone temperature is invalid even if
> polling is not enabled for the thermal zone (however, if this
> continues to fail, give up after some time).
> 
> Fixes: 202aa0d4bb53 ("thermal: core: Do not call handle_thermal_trip() if zone temperature is invalid")
> Reported-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> Link: https://lore.kernel.org/linux-pm/dc1e6cba-352b-4c78-93b5-94dd033fca16@linaro.org
> Link: https://lore.kernel.org/linux-pm/2764814.mvXUDI8C0e@rjwysocki.net
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

On v6.10 I'm seeing the following messages spammed to the kernel log endlessly,
and reverting this commit fixes it.

    [  156.410567] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  156.666583] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  156.922598] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  157.178613] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  157.434636] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  157.690774] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  157.946659] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  158.202717] thermal thermal_zone0: failed to read out thermal zone (-61)
    [  158.458697] thermal thermal_zone0: failed to read out thermal zone (-61)

/sys/class/thermal/thermal_zone0/type contains "iwlwifi_1".

- Eric