drm/edid: Try harder to fix up base EDID blocks

Requiring the first byte of the EDID base block header to be 0 means we
don't fix up as many transfer errors as we could.  Instead have the
callers specify whether it's meant to be block 0 or not, and
conditionally run header fixup based on that.

Bugzilla: https://bugzilla.redhat.com/812890
Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index c6366e90041..f425379e5aa 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -149,13 +149,13 @@ EXPORT_SYMBOL(drm_edid_header_is_valid);
  * Sanity check the EDID block (base or extension).  Return 0 if the block
  * doesn't check out, or 1 if it's valid.
  */
-bool drm_edid_block_valid(u8 *raw_edid)
+bool drm_edid_block_valid(u8 *raw_edid, int block)
 {
         int i;
         u8 csum = 0;
         struct edid *edid = (struct edid *)raw_edid;
 
-        if (raw_edid[0] == 0x00) {
+        if (block == 0) {
                 int score = drm_edid_header_is_valid(raw_edid);
                 if (score == 8) ;
                 else if (score >= 6) {
@@ -219,7 +219,7 @@ bool drm_edid_is_valid(struct edid *edid)
                 return false;
 
         for (i = 0; i <= edid->extensions; i++)
-                if (!drm_edid_block_valid(raw + i * EDID_LENGTH))
+                if (!drm_edid_block_valid(raw + i * EDID_LENGTH, i))
                         return false;
 
         return true;
@@ -299,7 +299,7 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
         for (i = 0; i < 4; i++) {
                 if (drm_do_probe_ddc_edid(adapter, block, 0, EDID_LENGTH))
                         goto out;
-                if (drm_edid_block_valid(block))
+                if (drm_edid_block_valid(block, 0))
                         break;
                 if (i == 0 && drm_edid_is_zero(block, EDID_LENGTH)) {
                         connector->null_edid_counter++;
@@ -324,7 +324,7 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
                                   block + (valid_extensions + 1) * EDID_LENGTH,
                                   j, EDID_LENGTH))
                                 goto out;
-                        if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH)) {
+                        if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH, j)) {
                                 valid_extensions++;
                                 break;
                         }