FAILED: patch "[PATCH] drm/amd/display: Honor Broadcast RGB for BT.2020 RGB output" failed to apply to 6.18-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 7fca7acd60a228b62b4e9efa5f184738041e9564
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026091655-squabble-justify-d868@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7fca7acd60a228b62b4e9efa5f184738041e9564 Mon Sep 17 00:00:00 2001
From: Satyajit Roy <sroy14@alum.utk.edu>
Date: Sun, 30 Aug 2026 03:52:06 +0000
Subject: [PATCH] drm/amd/display: Honor Broadcast RGB for BT.2020 RGB output

amdgpu_dm_get_output_color_space() applies the Broadcast RGB connector
property to default RGB output, but always selects full-range output for
BT.2020 RGB. Consequently, explicitly selecting Limited has no effect on
the output CSC or AVI InfoFrame when HDR uses BT.2020 RGB.

Select COLOR_SPACE_2020_RGB_LIMITEDRANGE when the output encoding is RGB
and Broadcast RGB is Limited. Keep Automatic and Full at full range, and
leave YCbCr output unchanged.

Add KUnit coverage for limited-range RGB output through both BT.2020
connector colorspace values.

Fixes: 6eb4c13a3845 ("drm/amd/display: Support "Broadcast RGB" drm property")
Signed-off-by: Satyajit Roy <sroy14@alum.utk.edu>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 022236eaa63bbf65761aa8aec43f661451a94654)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
index d03773887214..154e1f35dcb1 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
@@ -756,10 +756,14 @@ amdgpu_dm_get_output_color_space(const struct dc_crtc_timing *dc_crtc_timing,
 		break;
 	case DRM_MODE_COLORIMETRY_BT2020_RGB:
 	case DRM_MODE_COLORIMETRY_BT2020_YCC:
-		if (dc_crtc_timing->pixel_encoding == PIXEL_ENCODING_RGB)
-			color_space = COLOR_SPACE_2020_RGB_FULLRANGE;
-		else
+		if (dc_crtc_timing->pixel_encoding == PIXEL_ENCODING_RGB) {
+			if (connector_state->hdmi.broadcast_rgb == DRM_HDMI_BROADCAST_RGB_LIMITED)
+				color_space = COLOR_SPACE_2020_RGB_LIMITEDRANGE;
+			else
+				color_space = COLOR_SPACE_2020_RGB_FULLRANGE;
+		} else {
 			color_space = COLOR_SPACE_2020_YCBCR_LIMITED;
+		}
 		break;
 	case DRM_MODE_COLORIMETRY_DEFAULT: /* ITU601 */
 	default:
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_connector_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_connector_test.c
index 0d2f9dbce0a9..212a7536e65b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_connector_test.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_connector_test.c
@@ -567,6 +567,23 @@ static void dm_test_output_color_space_bt2020_rgb(struct kunit *test)
 			(int)COLOR_SPACE_2020_RGB_FULLRANGE);
 }
 
+/**
+ * dm_test_output_color_space_bt2020_rgb_limited - Test limited BT.2020 RGB
+ * @test: The KUnit test context
+ */
+static void dm_test_output_color_space_bt2020_rgb_limited(struct kunit *test)
+{
+	struct dc_crtc_timing timing = {};
+	struct drm_connector_state state = {};
+
+	timing.pixel_encoding = PIXEL_ENCODING_RGB;
+	state.colorspace = DRM_MODE_COLORIMETRY_BT2020_RGB;
+	state.hdmi.broadcast_rgb = DRM_HDMI_BROADCAST_RGB_LIMITED;
+
+	KUNIT_EXPECT_EQ(test, (int)amdgpu_dm_get_output_color_space(&timing, &state),
+			(int)COLOR_SPACE_2020_RGB_LIMITEDRANGE);
+}
+
 /**
  * dm_test_output_color_space_bt2020_ycc - Test Output color space bt2020 ycc
  * @test: The KUnit test context
@@ -638,6 +655,24 @@ static void dm_test_output_color_space_bt2020_ycc_rgb_encoding(struct kunit *tes
 			(int)COLOR_SPACE_2020_RGB_FULLRANGE);
 }
 
+/**
+ * dm_test_output_color_space_bt2020_ycc_rgb_encoding_limited - Test limited
+ * BT.2020 RGB output selected through the BT.2020 YCC connector colorspace
+ * @test: The KUnit test context
+ */
+static void dm_test_output_color_space_bt2020_ycc_rgb_encoding_limited(struct kunit *test)
+{
+	struct dc_crtc_timing timing = {};
+	struct drm_connector_state state = {};
+
+	timing.pixel_encoding = PIXEL_ENCODING_RGB;
+	state.colorspace = DRM_MODE_COLORIMETRY_BT2020_YCC;
+	state.hdmi.broadcast_rgb = DRM_HDMI_BROADCAST_RGB_LIMITED;
+
+	KUNIT_EXPECT_EQ(test, (int)amdgpu_dm_get_output_color_space(&timing, &state),
+			(int)COLOR_SPACE_2020_RGB_LIMITEDRANGE);
+}
+
 /**
  * dm_test_output_color_space_bt2020_rgb_ycc_encoding - Test Output color space
  * bt2020 rgb with non-rgb pixel encoding falls back to limited ycbcr
@@ -5422,10 +5457,12 @@ static struct kunit_case amdgpu_dm_connector_tests[] = {
 	KUNIT_CASE(dm_test_output_color_space_bt709_y_only),
 	KUNIT_CASE(dm_test_output_color_space_oprgb),
 	KUNIT_CASE(dm_test_output_color_space_bt2020_rgb),
+	KUNIT_CASE(dm_test_output_color_space_bt2020_rgb_limited),
 	KUNIT_CASE(dm_test_output_color_space_bt2020_ycc),
 	KUNIT_CASE(dm_test_output_color_space_default_ycbcr709_y_only),
 	KUNIT_CASE(dm_test_output_color_space_default_ycbcr601),
 	KUNIT_CASE(dm_test_output_color_space_bt2020_ycc_rgb_encoding),
+	KUNIT_CASE(dm_test_output_color_space_bt2020_ycc_rgb_encoding_limited),
 	KUNIT_CASE(dm_test_output_color_space_bt2020_rgb_ycc_encoding),
 	/* Tests for amdgpu_dm_convert_dc_color_depth_into_bpc */
 	KUNIT_CASE(dm_test_convert_color_depth_bpc_mappings),