linux-kernel - Re: [RFC PATCH 11/13] drm/msm/disp/dpu1: Add support for DSC in topology

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Message-ID: <06ffdec5-8b12-c077-0c51-6ea9100b96a4@linaro.org>
Date:   Fri, 28 May 2021 13:39:29 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>, Rob Clark <robdclark@...il.com>
Cc:     linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Marek <jonathan@...ek.ca>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org
Subject: Re: [RFC PATCH 11/13] drm/msm/disp/dpu1: Add support for DSC in
 topology

On 21/05/2021 15:49, Vinod Koul wrote:
> For DSC to work we typically need a 2,2,1 configuration. This should
> suffice for resolutions upto 4k. For more resolutions like 8k this won't
> work.
> 
> Furthermore, we can use 1 DSC encoder in lesser resulutions, but that is
> not power efficient according to Abhinav, so it is recommended to always
> use 2 encoders.

Not power efficient because the second DSC would also be powered on or 
because single DSC enc would consume more power than two DSCs?

> 
> So for now we blindly create 2,2,1 topology when DSC is enabled
> 
> Co-developed-by: Abhinav Kumar <abhinavk@...eaurora.org>
> Signed-off-by: Abhinav Kumar <abhinavk@...eaurora.org>
> Signed-off-by: Vinod Koul <vkoul@...nel.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 18cb1274a8bb..bffb40085c67 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -609,8 +609,22 @@ static struct msm_display_topology dpu_encoder_get_topology(
>   	topology.num_enc = 0;
>   	topology.num_intf = intf_count;
>   
> +	drm_enc = &dpu_enc->base;
> +	priv = drm_enc->dev->dev_private;
> +	if (priv && priv->dsc) {
> +		/* In case of Display Stream Compression DSC, we would use
> +		 * 2 encoders, 2 line mixers and 1 interface
> +		 * this is power optimal and can drive upto (including) 4k
> +		 * screens
> +		 */
> +		topology.num_enc = 2;
> +		topology.num_intf = 1;
> +		topology.num_lm = 2;
> +	}
> +
>   	return topology;
>   }
> +
>   static int dpu_encoder_virt_atomic_check(
>   		struct drm_encoder *drm_enc,
>   		struct drm_crtc_state *crtc_state,
> 


-- 
With best wishes
Dmitry