Re: [PATCH v1 4/5] drm/msm/dpu: calculate DSC encoder parameters dynamically

From: Kuogee Hsieh
Date: Fri Apr 21 2023 - 17:31:16 EST



On 4/21/2023 2:13 PM, Dmitry Baryshkov wrote:
On 22/04/2023 00:07, Kuogee Hsieh wrote:

On 4/20/2023 5:27 PM, Dmitry Baryshkov wrote:
On 21/04/2023 02:25, Kuogee Hsieh wrote:
During DSC preparation, add run time calculation to figure out what
usage modes, split mode and merge mode, is going to be setup.

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 56 ++++++++++++++++-------------
  1 file changed, 32 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 2fdacf1..5677728 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -529,17 +529,9 @@ void dpu_encoder_helper_split_config(
  bool dpu_encoder_use_dsc_merge(struct drm_encoder *drm_enc)
  {
      struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
-    int i, intf_count = 0, num_dsc = 0;
+    struct msm_display_topology *topology = &dpu_enc->topology;
  -    for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
-        if (dpu_enc->phys_encs[i])
-            intf_count++;
-
-    /* See dpu_encoder_get_topology, we only support 2:2:1 topology */
-    if (dpu_enc->dsc)
-        num_dsc = 2;
-
-    return (num_dsc > 0) && (num_dsc > intf_count);
+    return (topology->num_dsc > topology->num_intf);
  }
    static void dpu_encoder_get_topology(
@@ -1861,41 +1853,57 @@ static void dpu_encoder_prep_dsc(struct dpu_encoder_virt *dpu_enc,
      struct dpu_encoder_phys *enc_master = dpu_enc->cur_master;
      struct dpu_hw_dsc *hw_dsc[MAX_CHANNELS_PER_ENC];
      struct dpu_hw_pingpong *hw_pp[MAX_CHANNELS_PER_ENC];
+    struct msm_display_topology *topology = &dpu_enc->topology;
      int this_frame_slices;
      int intf_ip_w, enc_ip_w;
-    int dsc_common_mode;
+    int dsc_common_mode = 0;
      int pic_width;
      u32 initial_lines;
+    int num_dsc, num_intf;
      int i;
        for (i = 0; i < MAX_CHANNELS_PER_ENC; i++) {
          hw_pp[i] = dpu_enc->hw_pp[i];
          hw_dsc[i] = dpu_enc->hw_dsc[i];
-
-        if (!hw_pp[i] || !hw_dsc[i]) {
-            DPU_ERROR_ENC(dpu_enc, "invalid params for DSC\n");
-            return;
-        }

Why?

MAX_CHANNELS_PER_ENC == 2

This works for dsi since it use 2 dsc encoder.

Since DP only use one dsc encoder, this will cause it return at loop 2 without execute dpu_encoder_dsc_pipe_cfg().

Then the loop should go up to num_dsc rather than MAX_CHANNELS_PER_ENC



      }
  -    dsc_common_mode = 0;
+    num_dsc = topology->num_dsc;
+    num_intf = topology->num_intf;
+
      pic_width = dsc->pic_width;
  -    dsc_common_mode = DSC_MODE_MULTIPLEX | DSC_MODE_SPLIT_PANEL;
      if (enc_master->intf_mode == INTF_MODE_VIDEO)
          dsc_common_mode |= DSC_MODE_VIDEO;
  +    /*
+     * If this encoder is driving more than one DSC encoder, they
+     * operate in tandem, same pic dimension needs to be used by
+     * each of them.(pp-split is assumed to be not supported)
+     *
+     */
+
      this_frame_slices = pic_width / dsc->slice_width;
      intf_ip_w = this_frame_slices * dsc->slice_width;
+    enc_ip_w = intf_ip_w;
+
+    intf_ip_w /= num_intf;
+
+    if (num_dsc > 1)
+        dsc_common_mode |= DSC_MODE_SPLIT_PANEL;
+
+    if (dpu_encoder_use_dsc_merge(&dpu_enc->base)) {
+        dsc_common_mode |= DSC_MODE_MULTIPLEX;
+        /*
+         * in dsc merge case: when using 2 encoders for the same
+         * stream, no. of slices need to be same on both the
+         * encoders.
+         */
+        enc_ip_w = intf_ip_w / 2;

So do you want to get enc_ip_w / 2 or enc_ip_w / num_intf / 2 here?
enc_ip_w / num_intf / 2

But previously we had enc_ip_w = intf_ip_w / 2. Was it because of the assumption that num_intf = 1?
i think so since there is no num_intf involve at previous code.


+    }
  -    /*
-     * dsc merge case: when using 2 encoders for the same stream,
-     * no. of slices need to be same on both the encoders.
-     */
-    enc_ip_w = intf_ip_w / 2;
      initial_lines = dpu_encoder_dsc_initial_line_calc(dsc, enc_ip_w);
  -    for (i = 0; i < MAX_CHANNELS_PER_ENC; i++)
+    for (i = 0; i < num_dsc; i++)
          dpu_encoder_dsc_pipe_cfg(dpu_enc, hw_dsc[i], hw_pp[i], dsc,
                      dsc_common_mode, initial_lines);
  }