From: Hans de Goede <hdegoede@redhat.com>
Date: Mon, 24 Nov 2014 12:47:13 +0000 (+0100)
Subject: edid: Add an edid_check_checksum() helper function
X-Git-Tag: v2015.04-rc1~156
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=e745d064b441dbf48eac4bc2c494263d54262dec;p=u-boot

edid: Add an edid_check_checksum() helper function

Add a helper function to check the checksum of an EDID data block.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Anatolij Gustschin <agust@denx.de>
---

diff --git a/common/edid.c b/common/edid.c
index e66108f24a..df797fcdd5 100644
--- a/common/edid.c
+++ b/common/edid.c
@@ -12,6 +12,7 @@
 
 #include <common.h>
 #include <edid.h>
+#include <errno.h>
 #include <linux/ctype.h>
 #include <linux/string.h>
 
@@ -29,6 +30,17 @@ int edid_check_info(struct edid1_info *edid_info)
 	return 0;
 }
 
+int edid_check_checksum(u8 *edid_block)
+{
+	u8 checksum = 0;
+	int i;
+
+	for (i = 0; i < 128; i++)
+		checksum += edid_block[i];
+
+	return (checksum == 0) ? 0 : -EINVAL;
+}
+
 int edid_get_ranges(struct edid1_info *edid, unsigned int *hmin,
 		    unsigned int *hmax, unsigned int *vmin,
 		    unsigned int *vmax)
diff --git a/include/edid.h b/include/edid.h
index d3cc5232de..a69f43a206 100644
--- a/include/edid.h
+++ b/include/edid.h
@@ -245,6 +245,15 @@ void edid_print_info(struct edid1_info *edid_info);
  */
 int edid_check_info(struct edid1_info *info);
 
+/**
+ * Check checksum of a 128 bytes EDID data block
+ *
+ * @param edid_block	EDID block data
+ *
+ * @return 0 on success, or a negative errno on error
+ */
+int edid_check_checksum(u8 *edid_block);
+
 /**
  * Get the horizontal and vertical rate ranges of the monitor.
  *