linux-kernel - Re: [PATCH] power: supply: core: return -EAGAIN on uninitialized read temp

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Message-ID: <b63ac8c6-213b-4307-8d33-48badee7881d@linaro.org>
Date: Fri, 5 Jul 2024 10:08:08 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Neil Armstrong <neil.armstrong@...aro.org>,
 Sebastian Reichel <sre@...nel.org>, Rhyland Klein <rklein@...dia.com>,
 Anton Vorontsov <cbouatmailru@...il.com>, Jenny TC <jenny.tc@...el.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-arm-msm@...r.kernel.org,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 regressions@...ts.linux.dev
Subject: Re: [PATCH] power: supply: core: return -EAGAIN on uninitialized read
 temp

On 05/07/2024 07:56, Krzysztof Kozlowski wrote:
> On 04/07/2024 18:41, Daniel Lezcano wrote:
>> On 04/07/2024 10:52, Neil Armstrong wrote:
>>> If the thermal core tries to update the temperature from an
>>> uninitialized power supply, it will swawn the following warning:
>>> thermal thermal_zoneXX: failed to read out thermal zone (-19)
>>>
>>> But reading from an uninitialized power supply should not be
>>> considered as a fatal error, but the thermal core expects
>>> the -EAGAIN error to be returned in this particular case.
>>>
>>> So convert -ENODEV as -EAGAIN to express the fact that reading
>>> temperature from an uninitialized power supply shouldn't be
>>> a fatal error, but should indicate to the thermal zone it should
>>> retry later.
>>>
>>> It notably removes such messages on Qualcomm platforms using the
>>> qcom_battmgr driver spawning warnings until the aDSP firmware
>>> gets up and the battery manager reports valid data.
>>
>> Is it possible to have the aDSP firmware ready first ?
> 
> I don't think so. ADSP firmware is a file, so as every firmware it can
> be loaded from rootfs, not initramfs (unlike this driver), or even missing.

Ok, said differently, can't we initialize the thermal zone after the 
firmware is loaded ?

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