linux-kernel - Re: [REPOST PATCH v4 10/13] drm/msm/disp/dpu1: Add support for DSC in topology

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Date:   Thu, 17 Feb 2022 22:44:17 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Rob Clark <robdclark@...il.com>, 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>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org
Subject: Re: [REPOST PATCH v4 10/13] drm/msm/disp/dpu1: Add support for DSC
 in topology

On 2022-02-10 16:04:20, Vinod Koul wrote:
> For DSC to work we typically need a 2,2,1 configuration. This should
> suffice for resolutions up to 4k. For more resolutions like 8k this won't
> work.
> 
> Also, it is better to use 2 LMs and DSC instances as half width results
> in lesser power consumption as compared to single LM, DSC at full width.
> 
> The panel has been tested only with 2,2,1 configuration, 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 | 13 +++++++++++++
>  drivers/gpu/drm/msm/msm_drv.h               |  2 ++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 95a7bf362e81..13ccb7b3cce5 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -574,8 +574,21 @@ static struct msm_display_topology dpu_encoder_get_topology(
>  	topology.num_enc = 0;
>  	topology.num_intf = intf_count;
>  
> +	if (dpu_enc->dsc) {
> +		/* In case of Display Stream Compression DSC, we would use
> +		 * 2 encoders, 2 line mixers and 1 interface

LM is a layer mixer, not a line mixer, right?

- Marijn

> +		 * this is power optimal and can drive up to (including) 4k
> +		 * screens
> +		 */
> +		topology.num_enc = 2;
> +		topology.num_dsc = 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,
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index 6425a42e997c..994d895d1a47 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -103,12 +103,14 @@ enum msm_event_wait {
>   * @num_enc:      number of compression encoder blocks used
>   * @num_intf:     number of interfaces the panel is mounted on
>   * @num_dspp:     number of dspp blocks used
> + * @num_dsc:      number of Display Stream Compression (DSC) blocks used
>   */
>  struct msm_display_topology {
>  	u32 num_lm;
>  	u32 num_enc;
>  	u32 num_intf;
>  	u32 num_dspp;
> +	u32 num_dsc;
>  };
>  
>  /**
> -- 
> 2.31.1
>