Re: PATCH] SPDIF out clock sync for via8235 / ALC650

[Takashi Iwai <tiwai@suse.de>]

Hi,

At 26 Nov 2002 12:42:12 +0100,
Antonin ENFRUN wrote:
> 
> I'm using alsa-driver 0.9.0rc6 on an Asus A7V8X (via8235 southbridge and
> ALC650 -ac97 compatible- codec).
> 
> PCM output is fine on the main analog channel, but SPDIF out is not
> working for any FS != 48khz. Looking at the source, the SPDIF out is
> initialised at 48Khz on startup, and there is no way to change it. But
> the ALC650 disable SPDIF out if SPDIF clock is not the same as the clock
> used on the corresponding ac-link channel (I don't know if it's a
> standard AC97 behaviour ?)
> 
> The patch included tracks clock change on the main DAC channel, and
> updates the SPDIF clock accordingly : it allows SPDIF out to output the
> main PCM channel, when the sample rate is 32K, 44.1K or 48K.

thanks for your patch!

we have already a method to change the spdif rate:
	snd_ac97_set_rate(ac97, AC97_SPDIF, rate);
but it didn't work properly.  so i fixed the relevant part based on
your patch.

to via82xx.c, the above call was just added, so that the spdif rate is
automatically changed.


> 
> If there is a better solution, let me know !
> 
> TODO:
> * Test for the codec used (if other codecs don't need this ?)
> * Check the channel/slot on AC97-SPSA to track the corresponding clock.
> 
> On a side note, how can I send PCM to the other channels (rear,
> lfe/front and spdif) ?

you can use 4 or 6 channel interleaved samples.

> And is there already an API to get/set the SPDIF clock ?

it's possible also to use a control "IEC958 Playback Default" and set
iec958 status bits.


ciao,

Takashi


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