[alsa-devel] [patch][saa7134] do not change mute state for capturing audio

Stas Sergeev stsp at list.ru
Sun Jul 24 21:00:34 CEST 2011

24.07.2011 22:36, Mauro Carvalho Chehab wrote:
> So, only people that has saa7134 with alsa stream that opted
> to wire the saa7134 device to the sound card, and with a strong
> interference at the default tunning frequency (400 MHz) would
> notice a problem.
No, the "strong interference" thing have nothing to
do with it, I think. My card detects signal sometimes,
not always. Otherwise it says this:
saa7134[0]/audio: audio carrier scan failed, using 5.500 MHz [default]
yet the moise is still there.
If you look into a tvaudio_thread() function, you'll
notice that it disables automute _unconditionally_!
saa7134_tvaudio_do_scan() also disables automute
That's why I think there are bugs. Can we start
from fixing at least this, and see what happens then?

>> Since I have no idea why it finds some carrier, I can't
>> fix that in any way. Or, maybe, not to call the scan
>> on driver init? What will that break?
> Analog tuners need to be tuned at the device init on a high frequency
> according with their datasheets, otherwise the PLL may fail.
Maybe, not disabling the automute when the scan
was started at init, rather than when it was requested
by an app?

> You're the first one that reported it, and the code is there for _years_.
> So, this is not a commonly noticed problem at all.
I am only the first one who reported it _to that list_.
I think most other reports were against pulseaudio.

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