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>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index d74239f..3989c18 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3422,17 +3422,117 @@ 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;

diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index a1441c5..b96031d 100644 (file)
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -202,6 +202,11 @@ struct detailed_timing {
 #define DRM_EDID_FEATURE_PM_SUSPEND       (1 << 6)
 #define DRM_EDID_FEATURE_PM_STANDBY       (1 << 7)
 
+#define DRM_EDID_HDMI_DC_48               (1 << 6)
+#define DRM_EDID_HDMI_DC_36               (1 << 5)
+#define DRM_EDID_HDMI_DC_30               (1 << 4)
+#define DRM_EDID_HDMI_DC_Y444             (1 << 3)
+
 struct edid {
        u8 header[8];
        /* Vendor & product info */