[alsa-devel] [RFC 3/4] OMAP3: McBSP: Add interface for transmit FIFO state query

[Liam Girdwood]

On Tue, 2010-03-02 at 15:52 +0200, Eero Nurkkala wrote:
> On Tue, 2010-03-02 at 14:39 +0100, Ujfalusi Peter (Nokia-D/Tampere)
> wrote:
> > New function for reading the XBUFFSTAT register, which holds
> > the fill state of the transmit buffer on McBSP.
> > 
> > Signed-off-by: Peter Ujfalusi <peter.ujfalusi at nokia.com>
> > ---
> 
> Reading the XBUFFSTAT register is by no means accurate.
> IIRC, it reports the buffer status incorrectly about 1/50 times
> on average (@ 48000khz); with simple math, it may be read during the DMA
> burst. Or is it guaranteed not being read during DMA transfer / have
> you otherwise verified the behavior?

I agree, I've also seen XBUFFSTAT giving complete garbage with mcbsp3.

Liam 

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