[alsa-devel] [RFC PATCH] Add combined clock support to Atmel SoC audio

[Sergey Lapin]

Hi, Ryan!

On Wed, Nov 24, 2010 at 11:05:11AM +1300, Ryan Mallon wrote:
> The following patch is one that has been floating around in various
> forms in our own internal trees for a while.
> 
> The Atmel SSC peripheral has seperate TX and RX clocks which use
> separate pins from the the micro. TF (frame) and TK (clock) for transmit
> and RF and RK for receive. Not all codecs have separate frame and bit
> clocks for transmit and receive so we want to be able to do both
> playback and capture using a single set of pins.
> 
> This patch introduces a combined clock mode for the Atmel SSC
> peripheral. Which allows playback and capture to use a single set of
> pins. Currently combined clock is only supported on the TF/TK pins (some
> incomplete support exists for using RF/RK).
> 
> I have tested this patch on our AT91SAM9G45 + TLV320AIC26 platform.
> Playback and capture work individually. Simultaneous playback and
> capture have been tested by connecting a loopback cable on the linein
> and lineout jacks and then doing:
> 
>   arecord -c 2 -f S16_LE -r 44100 > recording.wav &
>   aplay 500hz_sine.wav
> 
> This patch is posted as RFC since the approach is incomplete and a bit
> hackish. I am mostly interested in knowing if this is a sensible
> approach, and could be cleaned up for mainline inclusion, or if there is
> a better way to do this.
> 
> Signed-off-by: Ryan Mallon <ryan at bluewatersys.com>

I think it is also important to submit code, which uses it.
If you can't do it I might try to do this in a few days.
Also worth mentioning codec slave mode requirement for this to work.

All the best,
S.