[PATCH 6.18.y] drm/amd/display: Honor Broadcast RGB for BT.2020 RGB output

[Sasha Levin <sashal@kernel.org>]

From: Satyajit Roy <sroy14@alum.utk.edu>

[ Upstream commit 7fca7acd60a228b62b4e9efa5f184738041e9564 ]

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
[ adapted the hunk to the older get_output_color_space() function in amdgpu_dm.c. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 06eb499f13637..5226224cf7027 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6511,10 +6511,14 @@ 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:
-- 
2.53.0