linux-kernel - Re: [PATCH v6 1/8] power: sequencing: Add T-HEAD TH1520 GPU power sequencer driver

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Message-ID: <f41cd747-eb57-4e17-a3b1-8b30e0c6e84c@samsung.com>
Date: Mon, 23 Jun 2025 19:20:54 +0200
From: Michal Wilczynski <m.wilczynski@...sung.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
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 v6 1/8] power: sequencing: Add T-HEAD TH1520 GPU power
 sequencer driver



On 6/23/25 16:32, Bartosz Golaszewski wrote:
> On Mon, Jun 23, 2025 at 1:44 PM Michal Wilczynski
> <m.wilczynski@...sung.com> wrote:
>>
>> Introduce the pwrseq-thead-gpu driver, a power sequencer provider for
>> the Imagination BXM-4-64 GPU on the T-HEAD TH1520 SoC. This driver
>> controls an auxiliary device instantiated by the AON power domain.
>>
>> The TH1520 GPU requires a specific sequence to correctly initialize and
>> power down its resources:
>>  - Enable GPU clocks (core and sys).
>>  - De-assert the GPU clock generator reset (clkgen_reset).
>>  - Introduce a short hardware-required delay.
>>  - De-assert the GPU core reset. The power-down sequence performs these
>>    steps in reverse.
>>
>> Implement this sequence via the pwrseq_power_on and pwrseq_power_off
>> callbacks.
>>
>> Crucially, the driver's match function is called when a consumer (the
>> Imagination GPU driver) requests the "gpu-power" target. During this
>> match, the sequencer uses clk_bulk_get() and
>> reset_control_get_exclusive() on the consumer's device to obtain handles
>> to the GPU's "core" and "sys" clocks, and the GPU core reset.  These,
>> along with clkgen_reset obtained from parent aon node, allow it to
>> perform the complete sequence.
>>
>> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
>> Signed-off-by: Michal Wilczynski <m.wilczynski@...sung.com>
>> ---
> 
> [snip]
> 
>> +
>> +       /* Additionally verify consumer device has AON as power-domain */
>> +       if (pwr_spec.np != ctx->aon_node || pwr_spec.args[0] != TH1520_GPU_PD) {
>> +               of_node_put(pwr_spec.np);
>> +               return 0;
>> +       }
>> +
>> +       of_node_put(pwr_spec.np);
>> +
>> +       /* If a consumer is already bound, only allow a re-match from it */
>> +       if (ctx->consumer_node)
>> +               return ctx->consumer_node == dev->of_node;
>> +
> 
> That should be `!!(ctx->consumer_node == dev->of_node)` or preferably
> `ctx->consumer_node == dev->of_node ? 1 : 0`. I can amend it when
> applying if you have no objections. The rest looks good to me and I'd
> like to pick it up into pwrseq/for-next in the next two days.

Sure,
Thanks !

> 
> Bart
> 
> [snip]
> 

Best regards,
-- 
Michal Wilczynski <m.wilczynski@...sung.com>