linux-kernel - Re: [PATCH v4 0/6] RK3588 and Rock 5B dts additions: thermal, OPP and fan

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Date: Tue, 28 May 2024 16:05:04 +0200
From: Dragan Simic <dsimic@...jaro.org>
To: Alexey Charkov <alchark@...il.com>
Cc: Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
 Heiko Stuebner <heiko@...ech.de>, Daniel Lezcano
 <daniel.lezcano@...aro.org>, Viresh Kumar <viresh.kumar@...aro.org>, Chen-Yu
 Tsai <wens@...nel.org>, Diederik de Haas <didi.debian@...ow.org>,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/6] RK3588 and Rock 5B dts additions: thermal, OPP and
 fan

Hello Alexey and Heiko,

On 2024-05-28 11:49, Alexey Charkov wrote:
> On Mon, May 6, 2024 at 1:37 PM Alexey Charkov <alchark@...il.com> 
> wrote:
>> 
>> This enables thermal monitoring and CPU DVFS on RK3588(s), as well as
>> active cooling on Radxa Rock 5B via the provided PWM fan.
>> 
>> Some RK3588 boards use separate regulators to supply CPUs and their
>> respective memory interfaces, so this is handled by coupling those
>> regulators in affected boards' device trees to ensure that their
>> voltage is adjusted in step.
>> 
>> This also enables the built-in thermal sensor (TSADC) for all boards
>> that don't currently have it enabled, using the default CRU based
>> emergency thermal reset. This default configuration only uses on-SoC
>> devices and doesn't rely on any external wiring, thus it should work
>> for all devices (tested only on Rock 5B though).
>> 
>> The boards that have TSADC_SHUT signal wired to the PMIC reset line
>> can choose to override the default reset logic in favour of GPIO
>> driven (PMIC assisted) reset, but in my testing it didn't work on
>> Radxa Rock 5B - maybe I'm reading the schematic wrong and it doesn't
>> support PMIC assisted reset after all.
>> 
>> Fan control on Rock 5B has been split into two intervals: let it spin
>> at the minimum cooling state between 55C and 65C, and then accelerate
>> if the system crosses the 65C mark - thanks to Dragan for suggesting.
>> This lets some cooling setups with beefier heatsinks and/or larger
>> fan fins to stay in the quietest non-zero fan state while still
>> gaining potential benefits from the airflow it generates, and
>> possibly avoiding noisy speeds altogether for some workloads.
>> 
>> OPPs help actually scale CPU frequencies up and down for both cooling
>> and performance - tested on Rock 5B under varied loads. I've dropped
>> those OPPs that cause frequency reductions without accompanying 
>> decrease
>> in CPU voltage, as they don't seem to be adding much benefit in day to
>> day use, while the kernel log gets a number of "OPP is inefficient" 
>> lines.
>> 
>> Note that this submission doesn't touch the SRAM read margin updates 
>> or
>> the OPP calibration based on silicon quality which the downstream 
>> driver
>> does and which were mentioned in [1]. It works as it is (also 
>> confirmed by
>> Sebastian in his follow-up message [2]), and it is stable in my 
>> testing on
>> Rock 5B, so it sounds better to merge a simple version first and then
>> extend when/if required.
>> 
>> [1] 
>> https://lore.kernel.org/linux-rockchip/CABjd4YzTL=5S7cS8ACNAYVa730WA3iGd5L_wP1Vn9=f83RCORA@mail.gmail.com/
>> [2] 
>> https://lore.kernel.org/linux-rockchip/pkyne4g2cln27dcdu3jm7bqdqpmd2kwkbguiolmozntjuiajrb@gvq4nupzna4o/
>> 
>> Signed-off-by: Alexey Charkov <alchark@...il.com>
>> ---
> 
> Hi Heiko,
> 
> Do you think this can be merged for 6.11? Looks like there hasn't been
> any new feedback in a while, and it would be good to have frequency
> scaling in place for RK3588.
> 
> Please let me know if you have any reservations or if we need any
> broader discussion.

As I promised earlier, I was going to test this patch series in detail.
Alas, I haven't managed to do that yet, :/ due to many reasons, but
I still remain firmly committed to doing that.

Is -rc4 the cutoff for 6.11?  If so, there's still time and I'll do my
best to test and review these patches as soon as possible.