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Subject[PATCH 2/4] drm/edid: Ignore bad standard timings.
Date
Signed-off-by: Adam Jackson <ajax@redhat.com>
---
drivers/gpu/drm/drm_edid.c | 16 ++++++++++++++++
1 files changed, 16 insertions(+), 0 deletions(-)

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 @@ static struct drm_display_mode *drm_find_dmt(struct drm_device *dev,
}
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 @@ struct drm_display_mode *drm_mode_std(struct drm_device *dev,
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 */
--
1.6.4.2


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