From 4966b2a9351500cf36f424dfe7a683036fce5622 Mon Sep 17 00:00:00 2001 From: Christian Schmidt Date: Mon, 19 Dec 2011 20:03:43 +0100 Subject: [PATCH] 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 Reviewed-by: Adam Jackson Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_edid.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 478b122..ece03fc 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); } -- 2.7.4