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drm/amd/display: Fix HF-VSDB DSC bpc detection to be cumulative

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[Why & How]
The HDMI Forum VSDB reports the maximum DSC color depth a sink supports.
This maximum is cumulative: a sink that reports 12 bpc also supports 10
and 8 bpc.

The previous code used exact "== 10" and "== 12" comparisons chained with
else-if, so a 12 bpc sink only set frl_dsc_12bpc and never set
frl_dsc_10bpc, incorrectly narrowing the DSC bpc range usable with that
sink.

Use ">= 10" and a separate ">= 12" check so a sink advertising a higher
maximum also enables the lower DSC bit depths it supports.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Fangzhi Zuo <jerry.zuo@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 4523adbf4dca157aea96a6f28b4e7b7ebd4d5eda)
This commit is contained in:
Fangzhi Zuo 2026-08-26 17:47:41 -04:00 committed by Alex Deucher
parent 3001d2073d
commit 5d7e0cc4af
2 changed files with 4 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
View File

@ -1202,9 +1202,10 @@ void populate_hdmi_info_from_connector(bool enable_frl, struct drm_hdmi_info *hd
edid_caps->max_frl_rate = get_max_frl_rate(hdmi->max_lanes, hdmi->max_frl_rate_per_lane);
edid_caps->frl_dsc_support = hdmi->dsc_cap.v_1p2;
if (edid_caps->frl_dsc_support) {
if (hdmi->dsc_cap.bpc_supported == 10)
/* HF-VSDB DSC max bpc is cumulative: >=12 implies 10 and 8. */
if (hdmi->dsc_cap.bpc_supported >= 10)
edid_caps->frl_dsc_10bpc = true;
else if (hdmi->dsc_cap.bpc_supported == 12)
if (hdmi->dsc_cap.bpc_supported >= 12)
edid_caps->frl_dsc_12bpc = true;
edid_caps->frl_dsc_all_bpp = hdmi->dsc_cap.all_bpp;
edid_caps->frl_dsc_native_420 = hdmi->dsc_cap.native_420;

2
drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_helpers_test.c
View File

@ -909,7 +909,7 @@ static void dm_test_populate_hdmi_frl_dsc_12bpc(struct kunit *test)
KUNIT_EXPECT_EQ(test, caps->max_frl_rate, 2);
KUNIT_EXPECT_TRUE(test, caps->frl_dsc_support);
KUNIT_EXPECT_FALSE(test, caps->frl_dsc_10bpc);
KUNIT_EXPECT_TRUE(test, caps->frl_dsc_10bpc);
KUNIT_EXPECT_TRUE(test, caps->frl_dsc_12bpc);
KUNIT_EXPECT_EQ(test, caps->frl_dsc_max_slices, 7);
KUNIT_EXPECT_EQ(test, caps->frl_dsc_max_frl_rate, 1);