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authorChristian Schmidt <schmidt@digadd.de>2011-12-19 20:03:43 +0100
committerDave Airlie <airlied@redhat.com>2011-12-20 09:51:10 +0000
commit4966b2a9351500cf36f424dfe7a683036fce5622 (patch)
treec84d044d1838bb0e2184189832b4143de888923f /drivers
parenta0ab734d62ef4c35ffa5e39f9ec1e6d6284f05fa (diff)
Fix wrong assumptions in cea_for_each_detailed_block v2
The current logic misunderstands the spec about CEA 18byte descriptors. First, the spec doesn't state "detailed timing descriptors" but "18 byte descriptors", so any data record could be stored, mixed timings and other data, just as in the standard EDID. Second, the lower four bit of byte 3 of the CEA record do not contain the number of descriptors, but "the total number of DTDs defining native formats in the whole EDID [...], starting with the first DTD in the DTD list (which starts in the base EDID block)." A device can of course support non-native formats. As such the number can't be used to determine n, and the existing code will filter non-timing 18byte descriptors anyway. Signed-off-by: Christian Schmidt <schmidt@digadd.de> Reviewed-by: Adam Jackson <ajax@redhat.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/drm_edid.c19
1 files changed, 2 insertions, 17 deletions
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 478b122ad1b..ece03fc2d38 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -508,25 +508,10 @@ static void
cea_for_each_detailed_block(u8 *ext, detailed_cb *cb, void *closure)
{
int i, n = 0;
- u8 rev = ext[0x01], d = ext[0x02];
+ u8 d = ext[0x02];
u8 *det_base = ext + d;
- switch (rev) {
- case 0:
- /* can't happen */
- return;
- case 1:
- /* have to infer how many blocks we have, check pixel clock */
- for (i = 0; i < 6; i++)
- if (det_base[18*i] || det_base[18*i+1])
- n++;
- break;
- default:
- /* explicit count */
- n = min(ext[0x03] & 0x0f, 6);
- break;
- }
-
+ n = (127 - d) / 18;
for (i = 0; i < n; i++)
cb((struct detailed_timing *)(det_base + 18 * i), closure);
}