linux-kernel - [PATCH 1/2] KMS: fix EDID detailed timing vsync parsing

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Date:	Sat, 23 Mar 2013 15:38:22 +0100 (MET)
From:	Torsten Duwe <torsten@....de>
To:	David Airlie <airlied@...ux.ie>, torvalds@...ux-foundation.org
cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] KMS: fix EDID detailed timing vsync parsing


EDID spreads some values across multiple bytes; bit-fiddling is needed
to retrieve these. The current code to parse "detailed timings" has a
cut&paste error that results in a vsync offset of at most 15 lines
instead of 63. en.wikipedia.org/wiki/EDID "detailed timing" bytes
10+11 show why that needs to be a left shift.

Cc: stable@...r.kernel.org
Signed-off-by: Torsten Duwe <duwe@....de>

--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -896,7 +896,7 @@ static struct drm_display_mode *drm_mode
 	unsigned vblank = (pt->vactive_vblank_hi & 0xf) << 8 | pt->vblank_lo;
 	unsigned hsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 0xc0) << 2 | pt->hsync_offset_lo;
 	unsigned hsync_pulse_width = (pt->hsync_vsync_offset_pulse_width_hi & 0x30) << 4 | pt->hsync_pulse_width_lo;
-	unsigned vsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 0xc) >> 2 | pt->vsync_offset_pulse_width_lo >> 4;
+	unsigned vsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 0xc) << 2 | pt->vsync_offset_pulse_width_lo >> 4;
 	unsigned vsync_pulse_width = (pt->hsync_vsync_offset_pulse_width_hi & 0x3) << 4 | (pt->vsync_offset_pulse_width_lo & 0xf);
 
 	/* ignore tiny modes */

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