SAA7110 VCR bug (kernel 2.4.x and older)

[Wolfgang Scherr <scherr@net4you.at>]

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Hello all,

there is a problem in the SAA7110 driver in the 2.4.x releases (seen
with 2.4.19,2.4.20 in combination with DC10) regarding the VCR-Mode. As
I don't know who is maintaining the v4l stuff currently, I hope the
recipient list is sufficient. Otherwise I apologize for the
inconvinience and would like to ask to forward the problem to the
maintainer....

Problem: With some video source (camcorders, VCRs, ...), it might happen
that the grabber card gets out of sync (result is an instable picture on
the screen due to weak sync quality of the signal).

This problem was reported by several users.

Solution: Switching on the VCR mode of the SAA7110 video frontend
improves frame synchronisation. Simple patch (successfully tested)
added, no other impact on functionality noted. Optionally this bit could
be set/cleared by a module parameter - especially in future releases,
should be trivial - a patch can be provided by me if needed.

Such a functionality may be also available with other video codec
hardware and should be checked/implemented there accordingly.

Best regards,

Wolfgang


[Re: DC 10+ Verwackeltes Bild bei VHS]
Christian von Eichel-Streiber wrote:
> 
> Hallo Wolfgang,
> 
> leider muss ich Dich schon wieder "nerven".
> 
> Ich hatte gehofft, dass mit einer neuen Suse nicht alte Probleme wieder
> auftreten würden. Jetzt habe ich die aktuelle SuSE 8.2 und der Zoran treiber
> ist schlechter als vorher.
> 
> Leider kann ich aber auch dne Patch, den Du mir das letzte mal gesendet hast
> nicht einsetzen, da sich der Kernel dann beschwert, dass das Ding für den
> 2.4.19 kompiliert wäre unbd jetzt ist ja der 2.4.20 drauf.
> 
> Was kann ich machen, umm wieder an die gepatchte Version zu kommen?
> Auf der Suse-Seite habe ich keinen Hinweis zu einer Fehlerbereinigten Version
> gefunden.
> 
> Es wäre super nett, wenn Du mir noch mal helfen könntest.
> 
> Vielen Dank
> 
> Christian von Eichel-Streiber

[-- Attachment #2: saa7110.c.patch --]
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167c167
< 		saa7110_write(decoder,0x0D,0x86);
---
> 		saa7110_write(decoder,0x0D,0x06);
174c174
< 	saa7110_write(decoder,0x0D,0x86);
---
> 	saa7110_write(decoder,0x0D,0x06);
183c183
< 		saa7110_write(decoder,0x0D,0x87);
---
> 		saa7110_write(decoder,0x0D,0x07);
195c195
< 		0xF8, 0xF8, 0x60, 0x60, 0x00, 0x86, 0x18, 0x90,
---
> 		0xF8, 0xF8, 0x60, 0x60, 0x00, 0x06, 0x18, 0x90,
229,230c229,230
< 		printk(KERN_INFO "%s_attach: chip version %x, VCR mode\n", device->name, saa7110_read(decoder));
< 		saa7110_write(decoder,0x0D,0x86);
---
> 		DEBUG(printk(KERN_INFO "%s_attach: chip version %x\n", device->name, saa7110_read(decoder)));
> 		saa7110_write(decoder,0x0D,0x06);
307c307
< 				saa7110_write(decoder, 0x0D, 0x86);
---
> 				saa7110_write(decoder, 0x0D, 0x06);
313c313
< 				saa7110_write(decoder, 0x0D, 0x86);
---
> 				saa7110_write(decoder, 0x0D, 0x06);
318c318
< 				saa7110_write(decoder, 0x0D, 0x87);
---
> 				saa7110_write(decoder, 0x0D, 0x07);