linux-kernel - [PATCH v6 7/7] drm/amd: use fixed dsc bits-per-pixel from edid

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Message-ID: <20251126065126.54016-8-iam@lach.pw>
Date: Wed, 26 Nov 2025 07:51:26 +0100
From: Yaroslav Bolyukin <iam@...h.pw>
To: Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Cc: Harry Wentland <harry.wentland@....com>,
	Leo Li <sunpeng.li@....com>,
	Rodrigo Siqueira <siqueira@...lia.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Wayne Lin <Wayne.Lin@....com>,
	amd-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	Yaroslav Bolyukin <iam@...h.pw>
Subject: [PATCH v6 7/7] drm/amd: use fixed dsc bits-per-pixel from edid

VESA vendor header from DisplayID spec may contain fixed bit per pixel
rate, it should be used by drm driver for the modes that declare
they are only supported with the declared fixed bits per pixel value.

Signed-off-by: Yaroslav Bolyukin <iam@...h.pw>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

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 e6728fd12eeb..32370279283f 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6613,6 +6613,11 @@ static void fill_stream_properties_from_drm_display_mode(
 
 	stream->output_color_space = get_output_color_space(timing_out, connector_state);
 	stream->content_type = get_output_content_type(connector_state);
+
+	/* DisplayID Type VII pass-through timings. */
+	if (mode_in->dsc_passthrough_timings_support && info->dp_dsc_bpp_x16 != 0) {
+		stream->timing.dsc_fixed_bits_per_pixel_x16 = info->dp_dsc_bpp_x16;
+	}
 }
 
 static void fill_audio_info(struct audio_info *audio_info,
@@ -7071,6 +7076,7 @@ create_stream_for_sink(struct drm_connector *connector,
 	struct drm_display_mode mode;
 	struct drm_display_mode saved_mode;
 	struct drm_display_mode *freesync_mode = NULL;
+	struct drm_display_mode *dsc_passthru_mode = NULL;
 	bool native_mode_found = false;
 	bool recalculate_timing = false;
 	bool scale = dm_state->scaling != RMX_OFF;
@@ -7162,6 +7168,16 @@ create_stream_for_sink(struct drm_connector *connector,
 		}
 	}
 
+	list_for_each_entry(dsc_passthru_mode, &connector->modes, head) {
+		if (dsc_passthru_mode->hdisplay == mode.hdisplay &&
+		    dsc_passthru_mode->vdisplay == mode.vdisplay &&
+		    drm_mode_vrefresh(dsc_passthru_mode) == mode_refresh) {
+			mode.dsc_passthrough_timings_support =
+				dsc_passthru_mode->dsc_passthrough_timings_support;
+			break;
+		}
+	}
+
 	if (recalculate_timing)
 		drm_mode_set_crtcinfo(&saved_mode, 0);
 
-- 
2.51.2