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authorPaul Mackerras <paulus@samba.org>2006-08-08 17:09:11 +1000
committerPaul Mackerras <paulus@samba.org>2006-08-08 17:09:11 +1000
commit32bc6e095d75233e7c87cc6fa0e07942b124d194 (patch)
tree8f83ef9a23d52d1305878b65dd98fc22b09b7f3e /drivers/media/video/bt8xx/bttv-vbi.c
parent5cf13911b1e72707b6f0eb39b2d819ec6e343d76 (diff)
parent81b73dd92b97423b8f5324a59044da478c04f4c4 (diff)
Merge branch 'merge'
Diffstat (limited to 'drivers/media/video/bt8xx/bttv-vbi.c')
-rw-r--r--drivers/media/video/bt8xx/bttv-vbi.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/media/video/bt8xx/bttv-vbi.c b/drivers/media/video/bt8xx/bttv-vbi.c
index 8c9f0f7cf467..63676e7bd635 100644
--- a/drivers/media/video/bt8xx/bttv-vbi.c
+++ b/drivers/media/video/bt8xx/bttv-vbi.c
@@ -31,11 +31,16 @@
#include <asm/io.h>
#include "bttvp.h"
-/* Offset from line sync pulse leading edge (0H) in 1 / sampling_rate:
- bt8x8 /HRESET pulse starts at 0H and has length 64 / fCLKx1 (E|O_VTC
- HSFMT = 0). VBI_HDELAY (always 0) is an offset from the trailing edge
- of /HRESET in 1 / fCLKx1, and the sampling_rate tvnorm->Fsc is fCLKx2. */
-#define VBI_OFFSET ((64 + 0) * 2)
+/* Offset from line sync pulse leading edge (0H) to start of VBI capture,
+ in fCLKx2 pixels. According to the datasheet, VBI capture starts
+ VBI_HDELAY fCLKx1 pixels from the tailing edgeof /HRESET, and /HRESET
+ is 64 fCLKx1 pixels wide. VBI_HDELAY is set to 0, so this should be
+ (64 + 0) * 2 = 128 fCLKx2 pixels. But it's not! The datasheet is
+ Just Plain Wrong. The real value appears to be different for
+ different revisions of the bt8x8 chips, and to be affected by the
+ horizontal scaling factor. Experimentally, the value is measured
+ to be about 244. */
+#define VBI_OFFSET 244
#define VBI_DEFLINES 16
#define VBI_MAXLINES 32