common: edid: Search for valid timing in extension block

One of my monitors have only 4k@60 timing in base EDID block which is
out of range for devices with HDMI 1.4. It turns out that it has
additional detailed timings in CTA-861 Extension Block and two of them
are appropriate for HDMI 1.4.

Add additional search for valid detailed timing in extension block.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

diff --git a/common/edid.c b/common/edid.c
index a6c875d9c8e8d81a96e196aad4c4509fe11fe783..fa85bcd6a152845e8d851fb56dfc5054d291b8b6 100644 (file)
--- a/common/edid.c
+++ b/common/edid.c
@@ -220,6 +220,24 @@ int edid_get_timing_validate(u8 *buf, int buf_size,
        /* Look for detailed timing in base EDID */
        found = edid_find_valid_timing(edid->monitor_details.descriptor, 4,
                                       timing, mode_valid, mode_valid_priv);
+
+       /* Look for detailed timing in CTA-861 Extension Block */
+       if (!found && edid->extension_flag && buf_size >= EDID_EXT_SIZE) {
+               struct edid_cea861_info *info =
+                       (struct edid_cea861_info *)(buf + sizeof(*edid));
+
+               if (info->extension_tag == EDID_CEA861_EXTENSION_TAG) {
+                       int count = EDID_CEA861_DTD_COUNT(*info);
+                       int offset = info->dtd_offset;
+                       int size = count * sizeof(struct edid_detailed_timing);
+
+                       if (offset >= 4 && offset + size < EDID_SIZE)
+                               found = edid_find_valid_timing(
+                                       (u8 *)info + offset, count, timing,
+                                       mode_valid, mode_valid_priv);
+               }
+       }
+
        if (!found)
                return -EINVAL;