On Thursday 19 October 2006 18:38, Eric Paynter wrote:
> On Wed, October 18, 2006 2:41 pm, Hans Verkuil said:
> > Kernel 2.6.18 contains full support for the tuner based on the
> > datasheets (a bit called the 'Low Noise Amplifier' had to be set).
> > Older kernels did not set that bit and so have poor quality.
>
> Is this the same bit that I posted a patch for 2.6.17 kernels a few
> months ago? Looked something like this:
Yes, it is.
>
>
> --- tuner-types.c 2006-08-27 10:52:28.000000000 -0700
> +++ tuner-types.c.patched 2006-08-27 10:53:05.000000000 -0700
> @@ -995,9 +995,9 @@
> /* ------------ TUNER_SAMSUNG_TCPN_2121P30A - Samsung NTSC
> ------------ */
>
> static struct tuner_range tuner_samsung_tcpn_2121p30a_ntsc_ranges[]
> = { - { 16 * 130.00 /*MHz*/, 0xce, 0x01, },
> - { 16 * 364.50 /*MHz*/, 0xce, 0x02, },
> - { 16 * 999.99 , 0xce, 0x08, },
> + { 16 * 130.00 /*MHz*/, 0xce, 0x01+4, },
> + { 16 * 364.50 /*MHz*/, 0xce, 0x02+4, },
> + { 16 * 999.99 , 0xce, 0x08+4, },
> };
>
>
>
> Anyhow, just to be sure I wasn't missing anything, I upgraded to
> 2.6.18 and ivtv 0.8.0. It didn't seem to change anything.
What sort of problems do you have? If it is noisy, then it is the signal
quality and I suggest you try an amplifier. I have also seen reports of
a 'herringbone' pattern that disappears when the '+4' is removed. The
PAL datasheet has a flowchart that shows when to set the bit (although
I had very confusing test results and it is not implemented at the
moment). No such chart is present in the NTSC datasheet, but perhaps a
similar thing is needed. However, the test for that is easy: remove
the '+4' and if that doesn't improve things, then you can be sure that
the tuner code is correct.
>
> > better than what's offered by the 2.6.18 kernel is unlikely to
> > happen. It should be equivalent to what the Windows driver does.
>
> You never know what a different set of eyes might discover. Isn't the
> whole philosophy of open source software that we all work together to
> achieve a better result?
I was asked not to redistribute the datasheet, so I won't. The code is
open source, but the datasheet isn't.
Regards,
Hans
>
> Thanks,
>
> -Eric
>
>
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