Re: [PATCH v2 09/11] drm/msm/disp/dpu1: Add support for DSC in topology

From: Dmitry Baryshkov
Date: Mon Oct 25 2021 - 10:37:37 EST


On 14/10/2021 17:13, Dmitry Baryshkov wrote:
On 07/10/2021 10:08, 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.

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@xxxxxxxxxxxxxx>
Signed-off-by: Abhinav Kumar <abhinavk@xxxxxxxxxxxxxx>
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
---
Changes since
RFC:
  - Add more details in changelog

  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 16 ++++++++++++++++
  1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index aac51c1bdf94..70f57a071165 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -538,6 +538,8 @@ static struct msm_display_topology dpu_encoder_get_topology(
              struct drm_display_mode *mode)
  {
      struct msm_display_topology topology = {0};
+    struct drm_encoder *drm_enc;
+    struct msm_drm_private *priv;
      int i, intf_count = 0;
      for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
@@ -572,8 +574,22 @@ 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;

So, here you'd set the topology.num_rm.

I meant 'num_dsc', please excuse the typo.


+    }
+
      return topology;
  }
+
  static int dpu_encoder_virt_atomic_check(
          struct drm_encoder *drm_enc,
          struct drm_crtc_state *crtc_state,





--
With best wishes
Dmitry