drm/edid: have edid_block_check() detect blocks that are all zero

We have the check function, have it also detect blocks that are all zero
instead of leaving that to callers.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f9ad302e6b7dbcd1dff98d94ec5500ce27bebe10.1649685475.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -1671,6 +1671,7 @@ EXPORT_SYMBOL(drm_edid_are_equal);
 enum edid_block_status {
 	EDID_BLOCK_OK = 0,
 	EDID_BLOCK_NULL,
+	EDID_BLOCK_ZERO,
 	EDID_BLOCK_HEADER_CORRUPT,
 	EDID_BLOCK_HEADER_REPAIR,
 	EDID_BLOCK_HEADER_FIXED,
@@ -1689,15 +1690,23 @@ static enum edid_block_status edid_block_check(const void *_block,
 	if (is_base_block) {
 		int score = drm_edid_header_is_valid(block);
 
-		if (score < clamp(edid_fixup, 0, 8))
-			return EDID_BLOCK_HEADER_CORRUPT;
+		if (score < clamp(edid_fixup, 0, 8)) {
+			if (edid_block_is_zero(block))
+				return EDID_BLOCK_ZERO;
+			else
+				return EDID_BLOCK_HEADER_CORRUPT;
+		}
 
 		if (score < 8)
 			return EDID_BLOCK_HEADER_REPAIR;
 	}
 
-	if (edid_block_compute_checksum(block) != edid_block_get_checksum(block))
-		return EDID_BLOCK_CHECKSUM;
+	if (edid_block_compute_checksum(block) != edid_block_get_checksum(block)) {
+		if (edid_block_is_zero(block))
+			return EDID_BLOCK_ZERO;
+		else
+			return EDID_BLOCK_CHECKSUM;
+	}
 
 	if (is_base_block) {
 		if (block->version != 1)
@@ -1785,7 +1794,7 @@ bool drm_edid_block_valid(u8 *_block, int block_num, bool print_bad_edid,
 	}
 
 	if (!valid && print_bad_edid) {
-		if (edid_block_is_zero(block)) {
+		if (status == EDID_BLOCK_ZERO) {
 			pr_notice("EDID block is all zeroes\n");
 		} else {
 			pr_notice("Raw EDID:\n");