drm/edid: Parse and handle HDMI deep color modes.

Check the HDMI cea block for deep color mode bits. If available,
assign the highest supported bpc for a hdmi display, corresponding
to the given deep color modes.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 108 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index d74239fec291..3989c185579f 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3423,16 +3423,116 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
 EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
 
 /**
+ * drm_assign_hdmi_deep_color_info - detect whether monitor supports
+ * hdmi deep color modes and update drm_display_info if so.
+ *
+ * @edid: monitor EDID information
+ * @info: Updated with maximum supported deep color bpc and color format
+ *        if deep color supported.
+ *
+ * Parse the CEA extension according to CEA-861-B.
+ * Return true if HDMI deep color supported, false if not or unknown.
+ */
+static bool drm_assign_hdmi_deep_color_info(struct edid *edid,
+                                            struct drm_display_info *info,
+                                            struct drm_connector *connector)
+{
+        u8 *edid_ext, *hdmi;
+        int i;
+        int start_offset, end_offset;
+        unsigned int dc_bpc = 0;
+
+        edid_ext = drm_find_cea_extension(edid);
+        if (!edid_ext)
+                return false;
+
+        if (cea_db_offsets(edid_ext, &start_offset, &end_offset))
+                return false;
+
+        /*
+         * Because HDMI identifier is in Vendor Specific Block,
+         * search it from all data blocks of CEA extension.
+         */
+        for_each_cea_db(edid_ext, i, start_offset, end_offset) {
+                if (cea_db_is_hdmi_vsdb(&edid_ext[i])) {
+                        /* HDMI supports at least 8 bpc */
+                        info->bpc = 8;
+
+                        hdmi = &edid_ext[i];
+                        if (cea_db_payload_len(hdmi) < 6)
+                                return false;
+
+                        if (hdmi[6] & DRM_EDID_HDMI_DC_30) {
+                                dc_bpc = 10;
+                                DRM_DEBUG("%s: HDMI sink does deep color 30.\n",
+                                                  drm_get_connector_name(connector));
+                        }
+
+                        if (hdmi[6] & DRM_EDID_HDMI_DC_36) {
+                                dc_bpc = 12;
+                                DRM_DEBUG("%s: HDMI sink does deep color 36.\n",
+                                                  drm_get_connector_name(connector));
+                        }
+
+                        if (hdmi[6] & DRM_EDID_HDMI_DC_48) {
+                                dc_bpc = 16;
+                                DRM_DEBUG("%s: HDMI sink does deep color 48.\n",
+                                                  drm_get_connector_name(connector));
+                        }
+
+                        if (dc_bpc > 0) {
+                                DRM_DEBUG("%s: Assigning HDMI sink color depth as %d bpc.\n",
+                                                  drm_get_connector_name(connector), dc_bpc);
+                                info->bpc = dc_bpc;
+
+                                /*
+                                 * Deep color support mandates RGB444 support for all video
+                                 * modes and forbids YCRCB422 support for all video modes per
+                                 * HDMI 1.3 spec.
+                                 */
+                                info->color_formats = DRM_COLOR_FORMAT_RGB444;
+
+                                /* YCRCB444 is optional according to spec. */
+                                if (hdmi[6] & DRM_EDID_HDMI_DC_Y444) {
+                                        info->color_formats |= DRM_COLOR_FORMAT_YCRCB444;
+                                        DRM_DEBUG("%s: HDMI sink does YCRCB444 in deep color.\n",
+                                                          drm_get_connector_name(connector));
+                                }
+
+                                /*
+                                 * Spec says that if any deep color mode is supported at all,
+                                 * then deep color 36 bit must be supported.
+                                 */
+                                if (!(hdmi[6] & DRM_EDID_HDMI_DC_36)) {
+                                        DRM_DEBUG("%s: HDMI sink should do DC_36, but does not!\n",
+                                                          drm_get_connector_name(connector));
+                                }
+
+                                return true;
+                        }
+                        else {
+                                DRM_DEBUG("%s: No deep color support on this HDMI sink.\n",
+                                                  drm_get_connector_name(connector));
+                        }
+                }
+        }
+
+        return false;
+}
+
+/**
  * drm_add_display_info - pull display info out if present
  * @edid: EDID data
  * @info: display info (attached to connector)
+ * @connector: connector whose edid is used to build display info
  *
  * Grab any available display info and stuff it into the drm_display_info
  * structure that's part of the connector.  Useful for tracking bpp and
  * color spaces.
  */
 static void drm_add_display_info(struct edid *edid,
-                                 struct drm_display_info *info)
+                                 struct drm_display_info *info,
+                                 struct drm_connector *connector)
 {
         u8 *edid_ext;
 
@@ -3462,6 +3562,9 @@ static void drm_add_display_info(struct edid *edid,
                         info->color_formats |= DRM_COLOR_FORMAT_YCRCB422;
         }
 
+        /* HDMI deep color modes supported? Assign to info, if so */
+        drm_assign_hdmi_deep_color_info(edid, info, connector);
+
         /* Only defined for 1.4 with digital displays */
         if (edid->revision < 4)
                 return;
@@ -3491,6 +3594,9 @@ static void drm_add_display_info(struct edid *edid,
                 break;
         }
 
+        DRM_DEBUG("%s: Assigning EDID-1.4 digital sink color depth as %d bpc.\n",
+                          drm_get_connector_name(connector), info->bpc);
+
         info->color_formats |= DRM_COLOR_FORMAT_RGB444;
         if (edid->features & DRM_EDID_FEATURE_RGB_YCRCB444)
                 info->color_formats |= DRM_COLOR_FORMAT_YCRCB444;
@@ -3549,7 +3655,7 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
         if (quirks & (EDID_QUIRK_PREFER_LARGE_60 | EDID_QUIRK_PREFER_LARGE_75))
                 edid_fixup_preferred(connector, quirks);
 
-        drm_add_display_info(edid, &connector->display_info);
+        drm_add_display_info(edid, &connector->display_info, connector);
 
         if (quirks & EDID_QUIRK_FORCE_8BPC)
                 connector->display_info.bpc = 8;