No sound comes out of AC97 codec

No sound comes out of AC97 codec

[Mohammed Amine SAYA]

Hi all,
I wrote a driver for an AC97 controller on ARM-based platform.
I followed the instructions in "Writing an ALSA Driver" tutorial.
I cross-compiled mplayer and I added some debug lines in my prepare, 
trigger and pointer
functions in the alsa driver. It seems that mplayer uses these functions 
but no sound comes out of
the speaker.
I put a scope to monitor AC97_TX, AC97_RX, AC97_CK and AC97_FS signals.
I was surprised to discover that nothing is sent. I decided to print the 
runtime->dma_addr to
see what kind of data the dma buffer contains. I only found out 
0x80008000 patterns and this
is exactly what I see on AC97_TX in slots 3 and 4 on the scope.

Where did the pcm data generated by mplayer go ?
Why the dma buffer is empty ? I use 
snd_pcm_lib_preallocate_pages_for_all and snd_pcm_lib_malloc_pages
to allocate the dma buffer.

The codec is detected correctly but the dma buffer is full of corrupted pcm.

Any lights on this please ?


Best regards,

Amine.



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Re: No sound comes out of AC97 codec

[Liam Girdwood]

On Fri, 2005-12-23 at 15:25 +0100, Mohammed Amine SAYA wrote:
> Hi all,
> I wrote a driver for an AC97 controller on ARM-based platform.

Can you tell us what your target cpu is ? 

> I decided to print the 
> runtime->dma_addr to
> see what kind of data the dma buffer contains. I only found out 
> 0x80008000 patterns and this
> is exactly what I see on AC97_TX in slots 3 and 4 on the scope.

ok, this means the ac97 controller on your cpu is probably running (as
it's sending data out on slots 3 and 4). Your DMA is probably also
working as it looks the buffer is being sent out on slots 3 and 4.

> 
> Where did the pcm data generated by mplayer go ?

Out of interest, have you tried using aplay and playing a wav file ?

> Why the dma buffer is empty ? I use 
> snd_pcm_lib_preallocate_pages_for_all and snd_pcm_lib_malloc_pages
> to allocate the dma buffer.
> 
> The codec is detected correctly but the dma buffer is full of corrupted pcm.
> 
> Any lights on this please ?
> 

It would probably help if you could post your code somewhere as it
sounds like a complex problem.

Liam



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Re: No sound comes out of AC97 codec

[Lee Revell]

On Fri, 2005-12-23 at 15:25 +0100, Mohammed Amine SAYA wrote:
> Hi all,
> I wrote a driver for an AC97 controller on ARM-based platform.

You forgot to post a link to your driver source.

Lee



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