[alsa-devel] commit b1ef29725865 (ACPI _REV=2) causes sound regression on Dell XPS 13 [Was: Discussion around quirking the _REV behavior for the XPS 13 (2015) until 4.2]

[Dominik Brodowski]

Mark,

On Tue, May 12, 2015 at 11:12:58AM +0100, Mark Brown wrote:
> > According to an off-list discussion, the sound breakage (and not just some
> > jack detection issue) seems to be caused due to alsa-lib being too old.
> 
> Right, it needs the userspace configuration files installing.

... and PulseAudio 6.0, as you stated in another message, but which is not in
Debian jessie. Therefore, commit b1ef29725865 does cause a regression (even
though it's just a side effect): the Dell XPS 13 (2013) works just fine with
a standard Debian jessie install and a current kernel. Sound worked fine
until commit b1ef29725865 / works fine with commit b1ef29725865 reverted.

New kernels should continue to work on (reasonably) old userspace; and
currently I do not see how this can be made to work with commit 
b1ef29725865 and no quirk / override. As soon as I find the time for that,
I'll try to create a patch for that -- unless someone beats me to that.

> > Under the no-regression rule, this means that either b1ef29725865 needs
> > to be reverted or we need to find another solution to this matter, such as
> > an override. And I think it is needed for longer than just for 4.1, as it
> > will continue to be cause regressions on quite recent userspace.
> 
> Does this also affect other behaviour of the system?  I'd be pretty
> unhappy if it introduce power regressions for example, I mostly don't use
> audio on my laptops but I care a lot about how long it'll run
> disconnected.  It *is* quite a new laptop and my experience installing
> was very much that it was in bringup (though quite a bit of this was
> userspace).

Well, sound _is_ quite important to me; and as stated above, the laptop
works just fine otherwise on Debian jessie (well, except the WiFi adapter,
but that's another story).

Best,
	Dominik
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