linux-kernel - Re: [PATCH v4 3/8] pmdomain: thead: Instantiate GPU power sequencer via auxiliary bus

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Message-ID: <CAMRc=MdrvZ0_3aWcmhYZP4CxOVbuYjL66iLPHKkDt=vCP7VN-Q@mail.gmail.com>
Date: Mon, 16 Jun 2025 11:10:31 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Michal Wilczynski <m.wilczynski@...sung.com>
Cc: Drew Fustini <drew@...7.com>, Guo Ren <guoren@...nel.org>, Fu Wei <wefu@...hat.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Frank Binns <frank.binns@...tec.com>, 
	Matt Coster <matt.coster@...tec.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>, 
	Ulf Hansson <ulf.hansson@...aro.org>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v4 3/8] pmdomain: thead: Instantiate GPU power sequencer
 via auxiliary bus

On Sat, Jun 14, 2025 at 8:09 PM Michal Wilczynski
<m.wilczynski@...sung.com> wrote:
>
> In order to support the complex power sequencing required by the TH1520
> GPU, the AON power domain driver must be responsible for initiating the
> corresponding sequencer driver. This functionality is specific to
> platforms where the GPU power sequencing hardware is controlled by the
> AON block.
>
> Extend the AON power domain driver to check for the presence of the
> "gpu-clkgen" reset in its own device tree node.
>
> If the property is found, create and register a new auxiliary device.
> This device acts as a proxy that allows the dedicated `pwrseq-thead-gpu`
> auxiliary driver to bind and take control of the sequencing logic.
>
> Signed-off-by: Michal Wilczynski <m.wilczynski@...sung.com>
> ---

[snip]

> +
> +static int th1520_pd_pwrseq_gpu_init(struct device *dev)
> +{
> +       struct auxiliary_device *adev;
> +       int ret;
> +
> +       /*
> +        * Correctly check only for the property's existence in the DT node.
> +        * We don't need to get/claim the reset here; that is the job of
> +        * the auxiliary driver that we are about to spawn.
> +        */
> +       if (of_property_match_string(dev->of_node, "reset-names",
> +                                    "gpu-clkgen") < 0)

If you use device_property_match_string() here, you don't need to pull
in of.h. It's typically preferred to use the top-level abstraction
unless not possible.

[snip]

Thanks,
Bartosz