[alsa-devel] [PATCH 3/3] ASoC: improve asynchronous mode support in the fsl_ssi driver

[Liam Girdwood]

On Tue, 2011-09-13 at 12:59 -0500, Timur Tabi wrote:
> The Freescale SSI audio controller supports "synchronous" and "asynchronous"
> modes.  In synchronous mode, playback and capture use the same input clock,
> so sample rates must be the same during simultaneous playback and capture.
> Unfortunately, the code which supports asynchronous mode is just broken in
> various ways.  In particular, it was constraining sample sizes as well as
> the sample rate.
> 
> The fix also allows us to simplify the code by eliminating the 'asynchronous',
> 'playback', and 'capture' variables that were used to keep track of playback
> and capture streams.
> 
> Unfortunately, it turns out that simulataneous playback and record does not
> actually work on the only platform that supports asynchronous mode: the
> Freescale P1022DS reference board.  If a second stream is started, the SSI
> grinds to halt for both streams.  This is true even if the P1022 is configured
> for synchronous mode, so it's likely a hardware problem that needs to be
> worked around.
> 
> Signed-off-by: Timur Tabi <timur at freescale.com>

Acked-by: Liam Girdwood <lrg at ti.com>