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: <hpmxj7tjmvbo55izoxgygqmysbabnpb35mprvn6w53vbtehnwe@yxmiigoeuyf3>
Date: Thu, 12 Dec 2024 00:24:12 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
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 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.


-- 
With best wishes
Dmitry