From: Harry Wentland <harry.wentland@amd.com>
Date: Fri, 16 Jan 2026 14:39:05 +0000 (-0500)
Subject: drm/amd/display: Set chroma taps to 1 if luma taps are 1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb51c5a103f63b6e9c3f9cebf7b1e2e1056d3119;p=thirdparty%2Flinux.git

drm/amd/display: Set chroma taps to 1 if luma taps are 1

When luma is unscaled we also want chroma to be pixel-perfect.
When luma taps are > 1 the result will be a blurred luma plane,
even when the image isn't scaled.

This makes IGT tests for CSC colorop pass.

Assisted-by: Claude: claude-sonnet-4.5
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---

diff --git a/drivers/gpu/drm/amd/display/dc/dpp/dcn10/dcn10_dpp.c b/drivers/gpu/drm/amd/display/dc/dpp/dcn10/dcn10_dpp.c
index ce91e5d289567..0e70ffc784b19 100644
--- a/drivers/gpu/drm/amd/display/dc/dpp/dcn10/dcn10_dpp.c
+++ b/drivers/gpu/drm/amd/display/dc/dpp/dcn10/dcn10_dpp.c
@@ -172,10 +172,14 @@ bool dpp1_get_optimal_number_of_taps(
 		scl_data->taps.h_taps_c = in_taps->h_taps_c;
 
 	if (!dpp->ctx->dc->debug.always_scale) {
-		if (IDENTITY_RATIO(scl_data->ratios.horz))
+		if (IDENTITY_RATIO(scl_data->ratios.horz)) {
 			scl_data->taps.h_taps = 1;
-		if (IDENTITY_RATIO(scl_data->ratios.vert))
+			scl_data->taps.h_taps_c = 1;
+		}
+		if (IDENTITY_RATIO(scl_data->ratios.vert)) {
 			scl_data->taps.v_taps = 1;
+			scl_data->taps.v_taps_c = 1;
+		}
 		if (IDENTITY_RATIO(scl_data->ratios.horz_c))
 			scl_data->taps.h_taps_c = 1;
 		if (IDENTITY_RATIO(scl_data->ratios.vert_c))
diff --git a/drivers/gpu/drm/amd/display/dc/dpp/dcn30/dcn30_dpp.c b/drivers/gpu/drm/amd/display/dc/dpp/dcn30/dcn30_dpp.c
index c7923531da83d..8a146968ee156 100644
--- a/drivers/gpu/drm/amd/display/dc/dpp/dcn30/dcn30_dpp.c
+++ b/drivers/gpu/drm/amd/display/dc/dpp/dcn30/dcn30_dpp.c
@@ -524,10 +524,14 @@ bool dpp3_get_optimal_number_of_taps(
 		scl_data->taps.v_taps_c = max_taps_c;
 
 	if (!dpp->ctx->dc->debug.always_scale) {
-		if (IDENTITY_RATIO(scl_data->ratios.horz))
+		if (IDENTITY_RATIO(scl_data->ratios.horz)) {
 			scl_data->taps.h_taps = 1;
-		if (IDENTITY_RATIO(scl_data->ratios.vert))
+			scl_data->taps.h_taps_c = 1;
+		}
+		if (IDENTITY_RATIO(scl_data->ratios.vert)) {
 			scl_data->taps.v_taps = 1;
+			scl_data->taps.v_taps_c = 1;
+		}
 		if (IDENTITY_RATIO(scl_data->ratios.horz_c))
 			scl_data->taps.h_taps_c = 1;
 		if (IDENTITY_RATIO(scl_data->ratios.vert_c))