[PATCH 1/3] drm/amd/display: Propagate HDMI RGB quantization selectability

From: Satyajit Roy

Date: Sat Aug 29 2026 - 23:52:48 EST


From: Satyajit Roy <sroy14@xxxxxxxxxxxx>

DC uses dc_edid_caps.qs_bit when constructing the HDMI AVI InfoFrame
quantization-range field. Although DRM parses the sink capability into
drm_display_info, DM never copies it into the DC EDID capabilities. The
field therefore remains zero and the AVI quantization range stays at its
default value.

Copy rgb_quant_range_selectable for HDMI sinks and extend the existing
EDID-capability KUnit test to cover it.

Fixes: 6eb4c13a3845 ("drm/amd/display: Support "Broadcast RGB" drm property")
Signed-off-by: Satyajit Roy <sroy14@xxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 1 +
.../drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index ab15ceec4da..e49a8dda512 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -218,6 +218,7 @@ enum dc_edid_status dm_helpers_parse_edid_caps(
edid_caps->edid_hdmi = connector->display_info.is_hdmi;

if (edid_caps->edid_hdmi) {
+ edid_caps->qs_bit = connector->display_info.rgb_quant_range_selectable;
populate_hdmi_info_from_connector(link->dc->config.enable_frl, &connector->display_info.hdmi, edid_caps);
drm_dbg_driver(connector->dev, "%s: HDMI_FRL [%s] max_frl_rate %d\n", __func__, connector->name, edid_caps->max_frl_rate);
if (edid_caps->frl_dsc_support)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c
index d4232648d8e..b13f258740c 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c
@@ -412,12 +412,14 @@ static void dm_test_parse_edid_caps_hdmi_frl(struct kunit *test)

/* Drive the HDMI/FRL branch */
connector->display_info.is_hdmi = true;
+ connector->display_info.rgb_quant_range_selectable = true;
connector->display_info.hdmi.scdc.supported = true;
connector->display_info.hdmi.max_lanes = 4;
connector->display_info.hdmi.max_frl_rate_per_lane = 12;

KUNIT_EXPECT_EQ(test, dm_helpers_parse_edid_caps(link, dc_edid, edid_caps), EDID_OK);
KUNIT_EXPECT_TRUE(test, edid_caps->edid_hdmi);
+ KUNIT_EXPECT_EQ(test, edid_caps->qs_bit, 1);
KUNIT_EXPECT_TRUE(test, edid_caps->scdc_present);
/* max_lanes 4 + max_frl_rate_per_lane 12 -> rate index 6 */
KUNIT_EXPECT_EQ(test, edid_caps->max_frl_rate, 6);
--
2.51.1