From: Zheng Yang <zhengyang@rock-chips.com>
Date: Mon, 24 Jul 2017 03:51:22 +0000 (+0800)
Subject: drm/edid: improve cea_db_offsets compatibility
X-Git-Tag: release-20171130_firefly~4^2~112
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=23e1058a945579f7a25f818d8fb5c41129979abe;p=firefly-linux-kernel-4.4.55.git

drm/edid: improve cea_db_offsets compatibility

The cea[2] is equal to the real value minus one in some sink edid,
found on a Konka LCD TV. the last data block offset plus the payload
length is equal to cea[2]. The end value need to plus one under this
scene.

Change-Id: I41b477559023ccd1cc4a5450dd9d35bed095f147
Signed-off-by: Zheng Yang <zhengyang@rock-chips.com>
---

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 3cd00c1a67cf..7461348954ed 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3449,6 +3449,23 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
 		*end = 127;
 	if (*end < 4 || *end > 127)
 		return -ERANGE;
+
+	/*
+	 * XXX: cea[2] is equal to the real value minus one in some sink edid.
+	 */
+	if (*end != 4) {
+		int i;
+
+		i = *start;
+		while (i < (*end) &&
+		       i + cea_db_payload_len(&(cea)[i]) < (*end))
+			i += cea_db_payload_len(&(cea)[i]) + 1;
+
+		if (cea_db_payload_len(&(cea)[i]) &&
+		    i + cea_db_payload_len(&(cea)[i]) == (*end))
+			(*end)++;
+	}
+
 	return 0;
 }