[U-Boot] [PATCH v2 07/11] edid: Add an edid_check_checksum() helper function

Hans de Goede
2014-12-19T17:10:37Z

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

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
common/edid.c | 12 ++++++++++++
include/edid.h | 9 +++++++++
2 files changed, 21 insertions(+)

diff --git a/common/edid.c b/common/edid.c
index e66108f..df797fc 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 d3cc523..a69f43a 100644
--- a/include/edid.h
+++ b/include/edid.h
@@ -246,6 +246,15 @@ 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.
*
* @param edid The EDID info
--
2.1.0