linux-kernel - Re: [PATCH v7 2/3] drm/msm/dpu: allow using two SSPP blocks for a single plane

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Message-ID: <cfbadc5a-6de0-4081-948c-3542c615a992@quicinc.com>
Date: Wed, 11 Dec 2024 14:38:09 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn
 Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 2/3] drm/msm/dpu: allow using two SSPP blocks for a
 single plane



On 12/11/2024 2:24 PM, Dmitry Baryshkov wrote:
> On Wed, Dec 11, 2024 at 01:51:51PM -0800, Abhinav Kumar wrote:
>>
>>
>> On 11/29/2024 5:55 PM, Dmitry Baryshkov wrote:
>>> Virtual wide planes give high amount of flexibility, but it is not
>>> always enough:
>>>
>>> In parallel multirect case only the half of the usual width is supported
>>> for tiled formats. Thus the whole width of two tiled multirect
>>> rectangles can not be greater than max_linewidth, which is not enough
>>> for some platforms/compositors.
>>>
>>> Another example is as simple as wide YUV plane. YUV planes can not use
>>> multirect, so currently they are limited to max_linewidth too.
>>>
>>> Now that the planes are fully virtualized, add support for allocating
>>> two SSPP blocks to drive a single DRM plane. This fixes both mentioned
>>> cases and allows all planes to go up to 2*max_linewidth (at the cost of
>>> making some of the planes unavailable to the user).
>>>
>>
>> Overall looks so much cleaner after unification!
>>
>> One small nit below,
>>
>>
>> You can still have,
>>
>> Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
>>
>> Note: we have started testing this series with sc7180 CrOS, and will report
>> our findings/ give tested-by this week.
>>
>>
>> <snip>
>>
>>> +static bool dpu_plane_try_multirect_parallel(struct dpu_sw_pipe *pipe, struct dpu_sw_pipe_cfg *pipe_cfg,
>>> +					     struct dpu_sw_pipe *r_pipe, struct dpu_sw_pipe_cfg *r_pipe_cfg,
>>> +					     struct dpu_hw_sspp *sspp, const struct msm_format *fmt,
>>> +					     uint32_t max_linewidth)
>>> +{
>>> +	r_pipe->sspp = NULL;
>>> +
>>> +	pipe->multirect_index = DPU_SSPP_RECT_SOLO;
>>> +	pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
>>> +
>>> +	r_pipe->multirect_index = DPU_SSPP_RECT_SOLO;
>>> +	r_pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
>>> +
>>
>>
>> There are two places where the multirect_index and multirect_mode are reset.
>> Would it be better to just have a small api dpu_plane_reset_multirect() and
>> do this there?
> 
> I'm not sure, what's the benefit. We can add an API to reset one pipe
> (to also be able to use it in _dpu_plane_atomic_disable()), but then
> it's just deduplication for the sake of deduplication.
> 

Yeah I was thinking something like

dpu_plane_reset_multirect(pipe);
dpu_plane_reset_multirect(r_pipe);

But its only a minor benefit, hence as I wrote it as a nit. We can keep 
things as it is, if its unnecessary in your opinion.


>