drm/amd/display: hide Apple Studio Display secondary tile

The Apple Studio Display exposes a 2x1 tiled panel over two SST DP
links. The primary tile advertises the full 5120x2880 mode (with DSC on
the bandwidth-sufficient link) while the secondary carries a per-tile
2560x2880 timing on a link without sufficient bandwidth. Report the
non-primary tile connector as disconnected during detect so compositors
only see the primary DP link and configure a single 5K mode instead of
driving both tiled streams independently.

Drive the behaviour from an EDID quirk: add a disable_second_tile panel
patch that apply_edid_quirks() sets for the affected Apple Studio
Display panel IDs (0xAE3A, 0xAE42, 0xAE46), and have detect() hide the
secondary tile when the sink carries that quirk.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Sun peng Li <sunpeng.li@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c

@@ -1643,6 +1643,39 @@ amdgpu_dm_connector_poll(struct amdgpu_dm_connector *aconnector, bool force)
 }
 EXPORT_IF_KUNIT(amdgpu_dm_connector_poll);
 
+/*
+ * Apple Studio Display exposes two SST DP links for a 2x1 tiled panel.
+ * The primary tile advertises the full 5120x2880 mode (with DSC on the
+ * bandwidth-sufficient link) while the secondary carries a per-tile
+ * 2560x2880 timing on a insufficient bandwidth link. Hide the secondary
+ * connector from userspace so compositors configure a single 5K stream
+ * on the primary link only.
+ */
+static bool amdgpu_dm_hide_secondary_tile_from_userspace(struct drm_connector *connector)
+{
+	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
+
+	if (!aconnector->dc_sink)
+		return false;
+
+	if (!aconnector->dc_sink->edid_caps.panel_patch.disable_second_tile)
+		return false;
+
+	drm_edid_connector_update(connector, aconnector->drm_edid);
+
+	if (!connector->has_tile)
+		return false;
+
+	if (!connector->tile_h_loc && !connector->tile_v_loc)
+		return false;
+
+	drm_dbg_kms(connector->dev,
+		    "[CONNECTOR:%d:%s] hiding secondary Apple Studio Display tile from userspace\n",
+		    connector->base.id, connector->name);
+
+	return true;
+}
+
 /**
  * amdgpu_dm_connector_detect() - Detect whether a DRM connector is connected to a display
  *
@@ -1686,6 +1719,9 @@ amdgpu_dm_connector_detect(struct drm_connector *connector, bool force)
 		(!aconnector->dc_sink || aconnector->dc_sink->edid_caps.analog))
 		return amdgpu_dm_connector_poll(aconnector, force);
 
+	if (amdgpu_dm_hide_secondary_tile_from_userspace(connector))
+		return connector_status_disconnected;
+
 	return (aconnector->dc_sink ? connector_status_connected :
 			connector_status_disconnected);
 }

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c

@@ -136,6 +136,17 @@ STATIC_IFN_KUNIT void apply_edid_quirks(struct dc_link *link, struct edid *edid,
 		drm_dbg_driver(dev, "Skip PHY SSC reduction on panel id %X\n", panel_id);
 		link->wa_flags.skip_phy_ssc_reduction = true;
 		break;
+	/*
+	 * Workaround for Apple Studio Display which exposes a 2x1 tiled panel
+	 * over two SST DP links. Hide the secondary tile from userspace so
+	 * compositors drive a single 5K stream on the primary link only.
+	 */
+	case drm_edid_encode_panel_id('A', 'P', 'P', 0xAE3A):
+	case drm_edid_encode_panel_id('A', 'P', 'P', 0xAE42):
+	case drm_edid_encode_panel_id('A', 'P', 'P', 0xAE46):
+		drm_dbg_driver(dev, "Hiding secondary tile on panel id %X\n", panel_id);
+		edid_caps->panel_patch.disable_second_tile = true;
+		break;
 	default:
 		return;
 	}

drivers/gpu/drm/amd/display/dc/dc_types.h

@@ -188,6 +188,7 @@ struct dc_panel_patch {
 	unsigned int skip_audio_sab_check;
 	unsigned int mst_start_top_delay;
 	unsigned int remove_sink_ext_caps;
+	bool disable_second_tile;
 	unsigned int disable_colorimetry;
 	uint8_t blankstream_before_otg_off;
 	bool oled_optimize_display_on;