linux-kernel - Re: [PATCH v5 13/21] drm/imagination: Add reset controller support for GPU initialization

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Message-ID: <c74db6a7-146b-4937-974d-2110b587f662@imgtec.com>
Date: Wed, 16 Apr 2025 16:53:31 +0000
From: Matt Coster <Matt.Coster@...tec.com>
To: Michal Wilczynski <m.wilczynski@...sung.com>
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Subject: Re: [PATCH v5 13/21] drm/imagination: Add reset controller support
 for GPU initialization

On 16/04/2025 15:25, Michal Wilczynski wrote:
> On 2/19/25 15:02, Michal Wilczynski wrote:
>> All IMG Rogue GPUs include a reset line that participates in the
>> power-up sequence. On some SoCs (e.g., T-Head TH1520 and Banana Pi
>> BPI-F3), this reset line is exposed and must be driven explicitly to
>> ensure proper initialization.  On others, such as the currently
>> supported TI SoC, the reset logic is handled in hardware or firmware
>> without exposing the line directly. In platforms where the reset line is
>> externally accessible, if it is not driven correctly, the GPU may remain
>> in an undefined state, leading to instability or performance issues.
>>
>> This commit adds a dedicated reset controller to the drm/imagination
>> driver.  By managing the reset line (where applicable) as part of normal
>> GPU bring-up, the driver ensures reliable initialization across
>> platforms regardless of whether the reset is controlled externally or
>> handled internally.
>>
>> Signed-off-by: Michal Wilczynski <m.wilczynski@...sung.com>
>> ---
>>  drivers/gpu/drm/imagination/pvr_device.c | 21 +++++++++++++++++++++
>>  drivers/gpu/drm/imagination/pvr_device.h |  9 +++++++++
>>  drivers/gpu/drm/imagination/pvr_power.c  | 22 +++++++++++++++++++++-
>>  3 files changed, 51 insertions(+), 1 deletion(-)
>>
> 
> Hi Matt,
> 
> This commit, along with the corresponding change in the DT bindings,
> doesn’t appear to conflict with the work you're doing for Rogue series
> enablement.

Agreed, it still applies cleanly on top of drm-misc-next after we landed
the BXS series.

> 
> Would you prefer if I re-send them as a mini-series so you can consider
> picking them up for the next kernel release?

That would be ideal, thank you!

Cheers,
Matt

> 
> Regards,
> Michał


-- 
Matt Coster
E: matt.coster@...tec.com


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