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Subject: Re: [PATCH v7 00/11] Stop monitoring disabled devices
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
To:     Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
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Date:   Thu, 2 Jul 2020 19:52:19 +0200
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On 02/07/2020 19:49, Daniel Lezcano wrote:

[ ... ]

>> Thanks!
>>
>> That confirms your suspicions.
>>
>> So the reason is that ->get_temp() is called while the mutex is held and
>> thermal_zone_device_is_enabled() wants to take the same mutex.
> 
> Yes, that's correct.
> 
>> Is adding a comment to thermal_zone_device_is_enabled() to never call
>> it while the mutex is held and adding another version of it which does
>> not take the mutex ok?
> 
> The thermal_zone_device_is_enabled() is only used in two places, acpi
> and this imx driver, and given:
> 
> 1. as soon as the mutex is released, there is no guarantee the thermal
> zone won't be changed right after, the lock is pointless, thus the
> information also.
> 
> 2. from a design point of view, I don't see why a driver should know if
> a thermal zone is disabled or not
> 
> It would make sense to end with this function and do not give the
> different drivers an opportunity to access this information.
> 
> Why not add change_mode for the acpi in order to enable or disable the
> events and for imx_thermal use irq_enabled flag instead of the thermal
> zone mode? Moreover it is very unclear why this function is needed in
> imx_get_temp(), and I suspect we should be able to get rid of it.

If you agree with that you can send a patch on top of your series so I
can test it fixes the imx platform.


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