drm/edid: Ignore bad standard timings.
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 3326987..dd35dc1 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -502,6 +502,19 @@
}
return mode;
}
+
+/*
+ * 0 is reserved. The spec says 0x01 fill for unused timings. Some old
+ * monitors fill with ascii space (0x20) instead.
+ */
+static int
+bad_std_timing(u8 a, u8 b)
+{
+ return (a == 0x00 && b == 0x00) ||
+ (a == 0x01 && b == 0x01) ||
+ (a == 0x20 && b == 0x20);
+}
+
/**
* drm_mode_std - convert standard mode info (width, height, refresh) into mode
* @t: standard timing params
@@ -525,6 +538,9 @@
unsigned vfreq = (t->vfreq_aspect & EDID_TIMING_VFREQ_MASK)
>> EDID_TIMING_VFREQ_SHIFT;
+ if (bad_std_timing(t->hsize, t->vfreq_aspect))
+ return NULL;
+
/* According to the EDID spec, the hdisplay = hsize * 8 + 248 */
hsize = t->hsize * 8 + 248;
/* vrefresh_rate = vfreq + 60 */