Description of problem: Recent Fedora kernels for F23 have disabled the CONFIG_ACPI_REV_OVERRIDE_POSSIBLE option. This causes a regression on Dell XPS 13 (9343) severe problems with audio playback. Version-Release number of selected component (if applicable): kernel-4.4.2 kernel-4.4.3 kernel-4.4.4 kernel-4.4.5 kernel-4.4.6 How reproducible: With any Fedora kernel 4.4.x so far Steps to Reproduce: 1. Upgrade from kernel 4.3 to 4.4 2. reboot twice 3. try to play audio Actual results: No audio. Expected results: Audio is available. Additional info: This is a clear regression. Please restore previous behavior by re-enabling CONFIG_ACPI_REV_OVERRIDE_POSSIBLE.
There is a discussion of this regression on LWN. http://lwn.net/Articles/680324/ Summary: - CONFIG_ACPI_REV_OVERRIDE_POSSIBLE only affects Dell XPS 13. - The code in question sets a flag that causes the kernel to revert to its <= 4.2 behavior. - The code is gated behind a DMI check that only runs on the specific laptop.
See also upstream bug. https://bugzilla.kernel.org/show_bug.cgi?id=114171 I don't think this is actually a pure kernel problem, a lot of userspace bits (mostly configs) are missing. First of all alsa-ucm should be installed and it's not, by default. Second an actual config matching laptops is missing. The actual config file[1] seems to be for a tablet. Result is jack detection (and automatic switch between speakers and headphones) is broken. [1] http://git.alsa-project.org/?p=alsa-lib.git;a=tree;f=src/conf/ucm/broadwell-rt286;hb=HEAD
(In reply to Enrico Tagliavini from comment #2) > I don't think this is actually a pure kernel problem, > a lot of userspace bits (mostly configs) are missing. That's besides the point. Audio worked with previous kernels. Due to a kernel upgrade it is now broken. This is a regression with an easy and known fix: simply restore CONFIG_ACPI_REV_OVERRIDE_POSSIBLE. Fixing userspace bits is always welcome, but this should have been done in the first place when the kernel was modified (when CONFIG_ACPI_REV_OVERRIDE_POSSIBLE was removed).
Sure agreed with it. I was just pointing out the primary source of the problem and that user space adjustment is needed more than a kernel code fix. The CONFIG_ACPI_REV_OVERRIDE_POSSIBLE could be switched off again when the userspace is actually fixed / updated / correctly configured to handled this hardware in I2S mode.
I run Fedora 23 on a Dell XPS 13 notebook (model 9343, bios A07). Since I upgraded to kernel 4.4 I have no audio. I filed a bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1313434 The problem persisted even after I upgraded alsa-lib and alsa-ucm to version 1.1.1-1. I filed a bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1313434 This is my primary working machine and this bug has been causing me a lot of trouble.
Laura Abbott and Justin Forbes: your input here would be appreciated.
F23 was rebased to 4.5.y.