linux-kernel - Re: [PATCH v3 4/5] cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states

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Date:   Mon, 24 Oct 2022 09:27:35 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Hector Martin <marcan@...can.st>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mark Kettenis <mark.kettenis@...all.nl>, asahi@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/5] cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states

On Mon, 24 Oct 2022 05:39:24 +0100,
Hector Martin <marcan@...can.st> wrote:
> 
> This driver implements CPU frequency scaling for Apple Silicon SoCs,
> including M1 (t8103), M1 Max/Pro/Ultra (t600x), and M2 (t8112).
> 
> Each CPU cluster has its own register set, and frequency management is
> fully automated by the hardware; the driver only has to write one
> register. There is boost frequency support, but the hardware will only
> allow their use if only a subset of cores in a cluster are in
> non-deep-idle. Since we don't support deep idle yet, these frequencies
> are not achievable, but the driver supports them. They will remain
> disabled in the device tree until deep idle is implemented, to avoid
> confusing users.
> 
> This driver does not yet implement the memory controller performance
> state tuning that usually accompanies higher CPU p-states. This will be
> done in a future patch.
> 
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  drivers/cpufreq/Kconfig.arm          |   9 +
>  drivers/cpufreq/Makefile             |   1 +
>  drivers/cpufreq/apple-soc-cpufreq.c  | 352 +++++++++++++++++++++++++++
>  drivers/cpufreq/cpufreq-dt-platdev.c |   2 +
>  4 files changed, 364 insertions(+)
>  create mode 100644 drivers/cpufreq/apple-soc-cpufreq.c
>

[...]

> +static struct freq_attr *apple_soc_cpufreq_hw_attr[] = {
> +	&cpufreq_freq_attr_scaling_available_freqs,
> +	NULL,
> +	NULL,

nit: extra NULL?

	M.

-- 
Without deviation from the norm, progress is not possible.