[alsa-devel] Handling HDA FIFO error
tiwai at suse.de
Wed May 15 12:08:53 CEST 2013
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.
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