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

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@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