[alsa-devel] Handling HDA FIFO error

[Takashi Iwai]

At Wed, 15 May 2013 11:08:55 +0200,
Clemens Ladisch wrote:
> 
> Daniel Drake wrote:
> > Digging into the HDA code, I can see that normally, when the stream
> > gets started, we get interrupts with SD_STS as 0x24. In the failure
> > case, as soon as we start the stream, we get a flood of interrupts
> > with SD_STS 0x8 - which indicates FIFO error.
> >
> > Disabling interrupt generation upon FIFO error does not help much - it
> > avoids the flood of interrupts, but doesn't change the fact that audio
> > playing apps hang or loop infinitely.
> >
> > Are there any things I could check that would explain why a FIFO error
> > might be occurring?
> 
> Probably a buffer underrun, i.e., the controller did not manage to
> read samples from memory fast enough.
> 
> > any suggestions for how to improve the hda_intel driver to handle
> > FIFO error gracefully? Right now there is no code to handle that.
> 
> It should stop the stream, i.e., go into the xrun state.
> 
> In theory, the application restarting the stream should reset the DMA
> engine enough to make it work again.  But you say this happens also
> when starting the stream, so I guess more resetting is needed.

Or possibly the coherency issue.  Try to disable snoop option.


Takashi