linux-kernel - Re: [v4l-dvb-maintainer] Re: [PATCH 00/23] V4L/DVB fixes

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Message-ID: <Pine.LNX.4.58.0607251741350.8253@shell3.speakeasy.net>
Date:	Tue, 25 Jul 2006 18:00:25 -0700 (PDT)
From:	Trent Piepho <xyzzy@...akeasy.org>
To:	Edgar Toernig <froese@....de>
cc:	v4l-dvb maintainer list <v4l-dvb-maintainer@...uxtv.org>,
	Mauro Carvalho Chehab <mchehab@...radead.org>, akpm@...l.org,
	Linux and Kernel Video <video4linux-list@...hat.com>,
	linux-kernel@...r.kernel.org, alan@...hat.com, torvalds@...l.org
Subject: Re: [v4l-dvb-maintainer] Re: [PATCH 00/23] V4L/DVB fixes

On Wed, 26 Jul 2006, Edgar Toernig wrote:
> I'm still missing the VBI_OFFSET fix.  See:
>
>   http://marc.theaimsgroup.com/?m=114710558215044
>
> Could you consider that patch for the next update and
> IMHO also for 2.6.16.x and 2.6.17.x?

I've put a patch that fixes this in my tree.  Mauro, please pull from
http://linuxtv.org/hg/~tap/v4l-dvb for:

02/02: bttv: Revert VBI_OFFSET to previous value, it works better
http://www.linuxtv.org/hg/~tap/v4l-dvb?cmd=changeset;node=88eaa291cc50;style=gitweb

FYI, contents of patch:
diff -r aaf8b9916bbb -r 88eaa291cc50 linux/drivers/media/video/bt8xx/bttv-vbi.c
--- a/linux/drivers/media/video/bt8xx/bttv-vbi.c        Tue Jul 25 16:37:03 2006
-0700
+++ b/linux/drivers/media/video/bt8xx/bttv-vbi.c        Tue Jul 25 17:51:36 2006
-0700
@@ -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

-
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