drm/edid: Retry EDID fetch up to four times
This matches the X server's retry logic. Note that we'll only retry if
we get a DDC response but fail validation; legitimately disconnected
outputs will bomb out early.
See also: http://bugzilla.redhat.com/532957
Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index dd95edf..2820082 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -133,9 +133,6 @@
DRM_ERROR("EDID has major version %d, instead of 1\n", edid->version);
goto bad;
}
- if (edid->revision > 4)
- DRM_DEBUG("EDID minor > 4, assuming backward compatibility\n");
-
for (i = 0; i < EDID_LENGTH; i++)
csum += raw_edid[i];
if (csum) {
@@ -143,6 +140,9 @@
goto bad;
}
+ if (edid->revision > 4)
+ DRM_DEBUG("EDID minor > 4, assuming backward compatibility\n");
+
return 1;
bad:
@@ -1060,19 +1060,19 @@
struct i2c_adapter *adapter,
char *buf, int len)
{
- int ret;
+ int i;
- ret = drm_do_probe_ddc_edid(adapter, buf, len);
- if (ret != 0) {
- goto end;
+ for (i = 0; i < 4; i++) {
+ if (drm_do_probe_ddc_edid(adapter, buf, len))
+ return -1;
+ if (edid_is_valid((struct edid *)buf))
+ return 0;
}
- if (!edid_is_valid((struct edid *)buf)) {
- dev_warn(&connector->dev->pdev->dev, "%s: EDID invalid.\n",
- drm_get_connector_name(connector));
- ret = -1;
- }
-end:
- return ret;
+
+ /* repeated checksum failures; warn, but carry on */
+ dev_warn(&connector->dev->pdev->dev, "%s: EDID invalid.\n",
+ drm_get_connector_name(connector));
+ return -1;
}
/**