Re: [PATCH 23/26] drm/amd/display: Correct DSC padding accounting

[Alex Hung]

On 11/20/25 11:33, Mario Limonciello wrote:

On 11/20/2025 12:03 PM, Alex Hung wrote:

From: Relja Vojvodic <rvojv...@amd.com>

[WHY]
- After the addition of all OVT patches, DSC padding was being accounted
   for multiple times, effectively doubling the padding

Can you double check when the OVT patches were submitted and if they were CC @stable?  If not; I think the stable tag should be dropped on this patch.

Thanks. I will remove the Cc stable.

- This caused compliance failures or corruption

[HOW]
- Add padding to DSC pic width when required by HW, and do not re-add
   when calculating reg values
- Do not add padding when computing PPS values, and instead track padding
   separately to add when calculating slice width values

Cc: Mario Limonciello <mario.limoncie...@amd.com>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Cc: sta...@vger.kernel.org
Reviewed-by: Chris Park <chris.p...@amd.com>
Reviewed-by: Wenjing Liu <wenjing....@amd.com>
Signed-off-by: Relja Vojvodic <rvojv...@amd.com>
Signed-off-by: Alex Hung <alex.h...@amd.com>
---
  drivers/gpu/drm/amd/display/dc/hwss/dcn314/dcn314_hwseq.c   | 2 +-
  drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c     | 2 +-
  drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c     | 2 +-
  drivers/gpu/drm/amd/display/dc/link/link_dpms.c             | 3 ++-
  .../gpu/drm/amd/display/dc/resource/dcn20/dcn20_resource.c  | 6 +++---
  5 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn314/dcn314_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn314/dcn314_hwseq.c

index 4ee6ed610de0..3e239124c17d 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn314/dcn314_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn314/dcn314_hwseq.c

@@ -108,7 +108,7 @@ static void update_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)

          dsc_cfg.dc_dsc_cfg = stream->timing.dsc_cfg;
          ASSERT(dsc_cfg.dc_dsc_cfg.num_slices_h % opp_cnt == 0);
          dsc_cfg.dc_dsc_cfg.num_slices_h /= opp_cnt;

-        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;

+        dsc_cfg.dsc_padding = 0;
          dsc->funcs->dsc_set_config(dsc, &dsc_cfg, &dsc_optc_cfg);
          dsc->funcs->dsc_enable(dsc, pipe_ctx->stream_res.opp->inst);

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c

index bf19ba65d09a..b213a2ac827a 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c

@@ -1061,7 +1061,7 @@ void dcn32_update_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)

          dsc_cfg.dc_dsc_cfg = stream->timing.dsc_cfg;
          ASSERT(dsc_cfg.dc_dsc_cfg.num_slices_h % opp_cnt == 0);
          dsc_cfg.dc_dsc_cfg.num_slices_h /= opp_cnt;

-        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;

+        dsc_cfg.dsc_padding = 0;
          if (should_use_dto_dscclk)

              dccg->funcs->set_dto_dscclk(dccg, dsc->inst, dsc_cfg.dc_dsc_cfg.num_slices_h); diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c

index 7aa0f452e8f7..cb2dfd34b5e2 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c

@@ -364,7 +364,7 @@ static void update_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)

          dsc_cfg.dc_dsc_cfg = stream->timing.dsc_cfg;
          ASSERT(dsc_cfg.dc_dsc_cfg.num_slices_h % opp_cnt == 0);
          dsc_cfg.dc_dsc_cfg.num_slices_h /= opp_cnt;

-        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;

+        dsc_cfg.dsc_padding = 0;
          dsc->funcs->dsc_set_config(dsc, &dsc_cfg, &dsc_optc_cfg);
          dsc->funcs->dsc_enable(dsc, pipe_ctx->stream_res.opp->inst);

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/ drivers/gpu/drm/amd/display/dc/link/link_dpms.c

index 1b1ce3839922..77e049917c4d 100644
--- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c

@@ -841,7 +841,7 @@ void link_set_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)

          dsc_cfg.dc_dsc_cfg = stream->timing.dsc_cfg;
          ASSERT(dsc_cfg.dc_dsc_cfg.num_slices_h % opp_cnt == 0);
          dsc_cfg.dc_dsc_cfg.num_slices_h /= opp_cnt;

-        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;

+        dsc_cfg.dsc_padding = 0;
          if (should_use_dto_dscclk)

              dccg->funcs->set_dto_dscclk(dccg, dsc->inst, dsc_cfg.dc_dsc_cfg.num_slices_h); @@ -857,6 +857,7 @@ void link_set_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)

          }
          dsc_cfg.dc_dsc_cfg.num_slices_h *= opp_cnt;
          dsc_cfg.pic_width *= opp_cnt;

+        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;           optc_dsc_mode = dsc_optc_cfg.is_pixel_format_444 ? OPTC_DSC_ENABLED_444 : OPTC_DSC_ENABLED_NATIVE_SUBSAMPLED; diff --git a/drivers/gpu/drm/amd/display/dc/resource/dcn20/ dcn20_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn20/ dcn20_resource.c

index 6679c1a14f2f..8d10aac9c510 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dcn20/dcn20_resource.c

@@ -1660,8 +1660,8 @@ bool dcn20_validate_dsc(struct dc *dc, struct dc_state *new_ctx)           if (pipe_ctx->top_pipe || pipe_ctx->prev_odm_pipe || !stream || !stream->timing.flags.DSC)

              continue;

-        dsc_cfg.pic_width = (stream->timing.h_addressable + stream- >timing.h_border_left

-                + stream->timing.h_border_right) / opp_cnt;

+        dsc_cfg.pic_width = (stream->timing.h_addressable + pipe_ctx- >dsc_padding_params.dsc_hactive_padding +                + stream->timing.h_border_left + stream- >timing.h_border_right) / opp_cnt;           dsc_cfg.pic_height = stream->timing.v_addressable + stream- >timing.v_border_top

                  + stream->timing.v_border_bottom;
          dsc_cfg.pixel_encoding = stream->timing.pixel_encoding;

@@ -1669,7 +1669,7 @@ bool dcn20_validate_dsc(struct dc *dc, struct dc_state *new_ctx)

          dsc_cfg.is_odm = pipe_ctx->next_odm_pipe ? true : false;
          dsc_cfg.dc_dsc_cfg = stream->timing.dsc_cfg;
          dsc_cfg.dc_dsc_cfg.num_slices_h /= opp_cnt;

-        dsc_cfg.dsc_padding = pipe_ctx- >dsc_padding_params.dsc_hactive_padding;

+        dsc_cfg.dsc_padding = 0;

          if (!pipe_ctx->stream_res.dsc->funcs- >dsc_validate_stream(pipe_ctx->stream_res.dsc, &dsc_cfg))

              return false;