[alsa-devel] trouble with alsa, wolfson, and TI OMAP35xx McBSP

Menon, Nishanth nm at ti.com
Wed Apr 22 20:05:40 CEST 2009

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org [mailto:linux-omap-
> owner at vger.kernel.org] On Behalf Of twebb
> Sent: Wednesday, April 22, 2009 12:58 PM

> Problem 2:
> Test tone is being presented by the user application, providing a 1Khz
> tone sampled at 44.1Khz. The data are S16_LE, right channel only. Left
> channel is quiet. The data seems to slip back and forth from left to
> right channel. This is reproducable and verified with a scope trace.
I recollect this issue from years back of OSS driver -> i2s is configured as dual phase - mcbsp sends data on both edges, and if the data write happen on the wrong edge for the wrong phase, we might get mix up.. if I recollect right, configuration for mcbsp was done as a single phase with the right edge as a trigger for transfer, the transfer size was set as 32 bytes (both channels).. this essentially guarentees that mcbsp will never mix up channels.

Nishanth Menon

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