drm/edid: Parse the HDMI CEA block and look for 4k modes

HDMI 1.4 adds 4 "4k x 2k" modes in the the CEA vendor specific block.

With this commit, we now parse this block and expose the 4k modes that
we find there.

v2: Fix the "4096x2160" string (nice catch!), add comments about
    do_hdmi_vsdb_modes() arguments and make it clearer that offset is
    relative to the end of the required fields of the HDMI VSDB
    (Ville Syrjälä)

v3: Fix 'Unknow' typo (Simon Farnsworth)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Tested-by: Cancan Feng <cancan.feng@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67030
Reviewed-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index bb25ee2..9de573c 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -931,6 +931,36 @@ static const struct drm_display_mode edid_cea_modes[] = {
         .vrefresh = 100, },
 };
 
+/*
+ * HDMI 1.4 4k modes.
+ */
+static const struct drm_display_mode edid_4k_modes[] = {
+       /* 1 - 3840x2160@30Hz */
+       { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+                  3840, 4016, 4104, 4400, 0,
+                  2160, 2168, 2178, 2250, 0,
+                  DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+         .vrefresh = 30, },
+       /* 2 - 3840x2160@25Hz */
+       { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+                  3840, 4896, 4984, 5280, 0,
+                  2160, 2168, 2178, 2250, 0,
+                  DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+         .vrefresh = 25, },
+       /* 3 - 3840x2160@24Hz */
+       { DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
+                  3840, 5116, 5204, 5500, 0,
+                  2160, 2168, 2178, 2250, 0,
+                  DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+         .vrefresh = 24, },
+       /* 4 - 4096x2160@24Hz (SMPTE) */
+       { DRM_MODE("4096x2160", DRM_MODE_TYPE_DRIVER, 297000,
+                  4096, 5116, 5204, 5500, 0,
+                  2160, 2168, 2178, 2250, 0,
+                  DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
+         .vrefresh = 24, },
+};
+
 /*** DDC fetch and block validation ***/
 
 static const u8 edid_header[] = {
@@ -2465,6 +2495,68 @@ do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
        return modes;
 }
 
+/*
+ * do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
+ * @connector: connector corresponding to the HDMI sink
+ * @db: start of the CEA vendor specific block
+ * @len: length of the CEA block payload, ie. one can access up to db[len]
+ *
+ * Parses the HDMI VSDB looking for modes to add to @connector.
+ */
+static int
+do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len)
+{
+       struct drm_device *dev = connector->dev;
+       int modes = 0, offset = 0, i;
+       u8 vic_len;
+
+       if (len < 8)
+               goto out;
+
+       /* no HDMI_Video_Present */
+       if (!(db[8] & (1 << 5)))
+               goto out;
+
+       /* Latency_Fields_Present */
+       if (db[8] & (1 << 7))
+               offset += 2;
+
+       /* I_Latency_Fields_Present */
+       if (db[8] & (1 << 6))
+               offset += 2;
+
+       /* the declared length is not long enough for the 2 first bytes
+        * of additional video format capabilities */
+       offset += 2;
+       if (len < (8 + offset))
+               goto out;
+
+       vic_len = db[8 + offset] >> 5;
+
+       for (i = 0; i < vic_len && len >= (9 + offset + i); i++) {
+               struct drm_display_mode *newmode;
+               u8 vic;
+
+               vic = db[9 + offset + i];
+
+               vic--; /* VICs start at 1 */
+               if (vic >= ARRAY_SIZE(edid_4k_modes)) {
+                       DRM_ERROR("Unknown HDMI VIC: %d\n", vic);
+                       continue;
+               }
+
+               newmode = drm_mode_duplicate(dev, &edid_4k_modes[vic]);
+               if (!newmode)
+                       continue;
+
+               drm_mode_probed_add(connector, newmode);
+               modes++;
+       }
+
+out:
+       return modes;
+}
+
 static int
 cea_db_payload_len(const u8 *db)
 {
@@ -2496,6 +2588,21 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
        return 0;
 }
 
+static bool cea_db_is_hdmi_vsdb(const u8 *db)
+{
+       int hdmi_id;
+
+       if (cea_db_tag(db) != VENDOR_BLOCK)
+               return false;
+
+       if (cea_db_payload_len(db) < 5)
+               return false;
+
+       hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);
+
+       return hdmi_id == HDMI_IDENTIFIER;
+}
+
 #define for_each_cea_db(cea, i, start, end) \
        for ((i) = (start); (i) < (end) && (i) + cea_db_payload_len(&(cea)[(i)]) < (end); (i) += cea_db_payload_len(&(cea)[(i)]) + 1)
 
@@ -2519,6 +2626,8 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
 
                        if (cea_db_tag(db) == VIDEO_BLOCK)
                                modes += do_cea_modes(connector, db + 1, dbl);
+                       else if (cea_db_is_hdmi_vsdb(db))
+                               modes += do_hdmi_vsdb_modes(connector, db, dbl);
                }
        }
 
@@ -2571,21 +2680,6 @@ monitor_name(struct detailed_timing *t, void *data)
                *(u8 **)data = t->data.other_data.data.str.str;
 }
 
-static bool cea_db_is_hdmi_vsdb(const u8 *db)
-{
-       int hdmi_id;
-
-       if (cea_db_tag(db) != VENDOR_BLOCK)
-               return false;
-
-       if (cea_db_payload_len(db) < 5)
-               return false;
-
-       hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);
-
-       return hdmi_id == HDMI_IDENTIFIER;
-}
-
 /**
  * drm_edid_to_eld - build ELD from EDID
  * @connector: connector corresponding to the HDMI/DP sink