linux-kernel - Re: [PATCH 09/21] drm/msm/dpu: request more mixer for 4K+ DSC case

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Message-ID: <CAA8EJppAaHtwaDLQVG6f4zTmhpkpuuF0-NK9-iB7UzFcwO3hdw@mail.gmail.com>
Date: Thu, 29 Aug 2024 14:11:57 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jun Nie <jun.nie@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/21] drm/msm/dpu: request more mixer for 4K+ DSC case

On Thu, 29 Aug 2024 at 13:20, Jun Nie <jun.nie@...aro.org> wrote:
>
> request more mixer for the case that hdisplay exceeding 4096
> and DSC enabled.

This doesn't seem to match the code. And it misses the _reason_ to do it.

>
> Signed-off-by: Jun Nie <jun.nie@...aro.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 05b203be2a9bc..33cfd94badaba 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -59,6 +59,7 @@
>  #define IDLE_SHORT_TIMEOUT     1
>
>  #define MAX_HDISPLAY_SPLIT 1080
> +#define MAX_HDISPLAY_DSC_SPLIT 2560
>
>  /* timeout in frames waiting for frame done */
>  #define DPU_ENCODER_FRAME_DONE_TIMEOUT_FRAMES 5
> @@ -588,15 +589,19 @@ static struct msm_display_topology dpu_encoder_get_topology(
>
>         /* Datapath topology selection
>          *
> -        * Dual display
> +        * Dual display without DSC
>          * 2 LM, 2 INTF ( Split display using 2 interfaces)
>          *
> +        * Dual display with DSC
> +        * 4 LM, 2 INTF ( Split display using 2 interfaces)

This doesn't match the code

> +        *
>          * Single display
>          * 1 LM, 1 INTF
>          * 2 LM, 1 INTF (stream merge to support high resolution interfaces)
>          *
>          * Add dspps to the reservation requirements if ctm is requested
>          */
> +
>         if (intf_count == 2)
>                 topology.num_lm = 2;
>         else if (!dpu_kms->catalog->caps->has_3d_merge)
> @@ -615,10 +620,21 @@ static struct msm_display_topology dpu_encoder_get_topology(
>                  * 2 DSC encoders, 2 layer mixers and 1 interface
>                  * this is power optimal and can drive up to (including) 4k
>                  * screens
> +                * But for dual display with hdisplay exceeding 4096, we need
> +                * 4 layer mixer. Because DSC has a max width of 2048 and
> +                * a single plane can only be used by one mixer pair
>                  */
> -               topology.num_dsc = 2;
> -               topology.num_lm = 2;
> -               topology.num_intf = 1;
> +
> +               if (intf_count == 2 &&
> +                   mode->hdisplay > MAX_HDISPLAY_DSC_SPLIT) {
> +                       topology.num_dsc = 4;
> +                       topology.num_lm = 4;
> +                       topology.num_intf = 2;
> +               } else {
> +                       topology.num_dsc = 2;
> +                       topology.num_lm = 2;
> +                       topology.num_intf = 1;
> +               }
>         }
>
>         return topology;
>
> --
> 2.34.1
>


-- 
With best wishes
Dmitry