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

Dmitry Baryshkov
2021-05-28T10:39:38Z

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@codeaurora.org>
> Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>
> Signed-off-by: Vinod Koul <vkoul@kernel.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