[alsa-devel] SoC Atmel SSC stereo problem

Clemens Ladisch clemens at ladisch.de
Fri Oct 22 18:11:57 CEST 2010

Patrick Ziegler wrote:
> I have some trouble with stereo audio through the atmal ssc interface
> based on at91-ssc.c.

(Merged into atmel_ssc_dai.c since about one year ago.)

> Unfortunately left and right channels were swapped periodically.
> In my environment the codec supplies the BLCK and LRC clocks and
> the SSC is configured to transmit one sample on both edges of the LRC clock.
> But I guess the audio frames will always start with a frame of the left channel
> while the LRC clock is in an undefined state.


> How does normally the audio driver detect when a left and when a right channel
> frame should be send and with which it should start ?

The driver cannot do anything about this; the hardware must be told
to start transmitting at the falling edge.

If possible.

Is there a reason why the codec supplies LRC?


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