Re: [PATCH] arm64: dts: juno: align thermal zone names with bindings

From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Rob Herring <robh+dt@kernel.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: juno: align thermal zone names with bindings
Date: Wed, 3 Jan 2024 11:13:18 +0100	[thread overview]
Message-ID: <b9943188-b3f9-472f-bc60-e8e6e043ddf4@linaro.org> (raw)
In-Reply-To: <CAL_JsqKogbT_4DPd1n94xqeHaU_J8ve5K09WOyVsRX3jxxUW3w@mail.gmail.com>

On 02/01/2024 19:09, Rob Herring wrote:
> On Sat, Dec 9, 2023 at 10:16 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> Thermal bindings require thermal zone node names to match
>> certain patterns:
>>
>>   juno.dtb: thermal-zones: 'big-cluster', 'gpu0', 'gpu1', 'little-cluster', 'pmic', 'soc'
>>     do not match any of the regexes: '^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$', 'pinctrl-[0-9]+'
> 
> You've just traded this warning for these:
> 
>       6  thermal-zones: 'little-cluster-thermal' does not match any of
> the regexes: '^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$',

Uh, now I wonder how did I see the warning going away.

> 'pinctrl-[0-9]+'
>       4  thermal-zones: gpu1-thermal: 'trips' is a required property
>       4  thermal-zones: gpu0-thermal: 'trips' is a required property
>       4  thermal-zones: big-cluster-thermal: 'trips' is a required property
> 
> Last I checked this, it looked like the length of the child names was
> limited because the thermal subsys uses the node names for its naming
> which is limited to 20 chars (with null). Though the regex here allows
> for 21 chars without nul. Looks like a double off by one error.

Yes, that's another issue.

> 
> The thought I had at the time was to make the kernel drop '-thermal'
> from its names. Might be an (Linux) ABI issue if userspace cares (I
> think it shouldn't). Also, I'm not sure how the kernel handles the
> names overflowing. Maybe it is fine and we can just extend the length
> in the schema from 12 to 18 (plus the 1 starting char).

The name is used in the "/sys/class/thermal/thermal_zone0/type" file, so
actually some userspace could depend on it, but it would be affected
anyway by my renaming of nodes.

Best regards,
Krzysztof