[alsa-devel] AT32AP7000 (AVR32) + WM8510
geoffrey at pager.net
Sat May 24 00:56:00 CEST 2008
On Thursday 22 May 2008 06:11:31 pm Geoffrey Wossum wrote:
> On Thursday 22 May 2008 05:48:41 pm Mark Brown wrote:
> > On Thu, May 22, 2008 at 02:57:41PM -0500, Geoffrey Wossum wrote:
> > > Looks like it should work to me. Note that I do hear a pop from the
> > > speaker the first time I try to play a file. Here's a dump of the
> > > registers while I'm trying to play a file with aplay. I'm combing
> > > through them right now to see if I can find anything that looks off.
> > I'll have a look at it at some point, but not right now :) . I should
> > also have asked you if you could post your machine driver - if you'd
> > rather post it off-list that'd be fine.
Ok, I got it working. It can now play "I'm sorry, Dave. I'm afraid I can't
do that." This should be the audio equivalent of "Hello world" :)
First, I changed it so the AVR32 provided the BCLK and FRAME. I could never
get the WM8510 to generate what looked like proper FRAMES. I did continue
using the WM8510's PLL to generate the DAC clock. With the AVR32 providing
the clocks, I at least got some noise out of it.
After a lot of head scratching and analyzing register settings and what not, I
realized that I had based my AVR32 platform drivers on the AT91. The AT91 is
little endian, the AVR32 is big endian. Changing all the SNDRV_PCM_FMTBIT_
settings to be BE instead of LE changed the noise into the files I was trying
Finally, I really had to lie in the wm8510 code and say that it supported a
minimum of 2 channels, and a maximum of 2 channels. This makes sense from
the data sheet, since it still wants a left and a right channel of data, and
just throws one away.
A few questions:
I had to change the WM8510's format to say that it wanted big endian. Should
the CODEC (and platform and machine) be setup just to say that it uses
SNDRV_PCM_FMTBIT_S16 instead of SNDRV_PCM_FMTBIT_S16_LE/BE? Looks from
sound/pcm.h this should just do the Right Thing.
Any idea why I couldn't get the WM8510 to generate the FRAME signal properly?
Like I said before, it generated a 44.1 kHz frame no matter the BCLK divider
or the word length were set to.
Thanks for the help! As soon as I get the code cleaned up some, I'll
contribute the AVR32 platform driver code.
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