[alsa-devel] HDA record fails with FIFO error

[David Henningsson]

On 2011-04-07 12:10, Takashi Iwai wrote:
> At Thu, 7 Apr 2011 16:54:50 +0800,
> Xu, Andiry wrote:
>>
>> Hi Takashi,
>>
>> Currently I encountered an HD audio issue reported by customer on a
>> Lenovo x100e system. Sometimes, but not always, when starting a
>> recording stream through the HDA controller, the controller generates a
>> large amount of interrupts (~40 000 interrupts per second). After this
>> has happened, jack sense (i e unsolicited events from the codec) stops
>> working until the next system reboot.

This seems more reproducible now than it was a while ago, now it seems 
to happen more often than not.

>> SD0STS returns a FIFO error (0x28) in interrupt handler. The interrupt
>> service routine acknowledges this error but does not do anything to
>> counteract the root cause to the problem, so it appears again and again.
>> Restarting the stream does not seem to help. Enable MSI or not does not
>> help either.
>>
>> The issue occurs on 2.6.35 and 2.6.38-rc8+, have not tried latest kernel
>> yet but I think it's also there. FIFO error indicates FIFO overrun
>> occurring while the RUN bit is set, but the driver simply acknowledge
>> and clear the error. I wonder what the root cause and the right
>> treatment are in this case. Any suggestions?

Brainstorming:
1) We could try adding udelays at random places.
2) There are a few workarounds for different chips already in 
hda_intel.c, maybe try applying them here as well.

Does that make sense to either of you?

> FIFO_ERR is actually never handled, so basically we can ignore.
> Simply disabling it like below works around your problem?
>
> Of course, a proper handling of FIFO error would be better, but
> this may need more code rewrites.

This does not fix the error in question, it removes the interrupts all 
right, but neither recording nor jack sense starts to work.

-- 
David Henningsson, Canonical Ltd.
http://launchpad.net/~diwic