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