[PATCH v3 4/9] common: edid: Search for valid timing in extension block

[Andre Przywara]

From: Jernej Skrabec <jernej.skrabec at siol.net>

One of my monitors have only 4k at 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 at siol.net>
Acked-by: Andre Przywara <andre.przywara at arm.com>
Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 common/edid.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/common/edid.c b/common/edid.c
index a6c875d9c8e..14d8836c360 100644
--- 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;
 
-- 
2.17.5