drm/edid: Fix preferred mode parse for EDID 1.4

In 1.4, the first detailed mode is always the preferred mode.  The bit
that used to mean that, now means "this mode is the physical size in
pixels".

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 9aa65b289d01..2e1298cf576f 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1295,7 +1295,10 @@ static int add_detailed_info(struct drm_connector *connector,
 
         for (i = 0; i < EDID_DETAILED_TIMINGS; i++) {
                 struct detailed_timing *timing = &edid->detailed_timings[i];
-                int preferred = (i == 0) && (edid->features & DRM_EDID_FEATURE_PREFERRED_TIMING);
+                int preferred = (i == 0);
+
+                if (preferred && edid->version == 1 && edid->revision < 4)
+                        preferred = (edid->features & DRM_EDID_FEATURE_PREFERRED_TIMING);
 
                 /* In 1.0, only timings are allowed */
                 if (!timing->pixel_clock && edid->version == 1 &&