Audio device not immediately recognized after booting Windows

[AdamDorwart]

I've tested this with the latest firmware (A04) and I'm on a fresh install of Ubuntu 15.04.

In a dual boot configuration it appears sound doesn't work. The hardware device doesn't appear to be recognized. To make matters strange the audio hardware is unrecognizable in Windows as well after a reboot and switching OSes. It takes two full reboots of Windows back to back in order to get the audio device to be recognized again.

[soren121]

Not a bug, this is just an unfortunate consequence of how the EC in this laptop works. On Windows, the EC is configured to init the audio in I2S mode, which I think provides battery savings and such. On Linux, the I2S driver isn't quite ready for use yet, so the EC configures audio in HDA mode. In order to switch between HDA and I2S, you must do two cold reboots. Once the Linux kernel gets complete I2S support, which should happen by either 4.2 or 4.3, this will no longer be a problem.

[dchambers]

@soren121, what is EC please?

[soren121]

@dchambers Embedded controller.

[AdamDorwart]

@soren121 So just to be clear, should audio work after two full reboots in both Ubuntu and Windows? At the moment I have no audio in Ubuntu 15.04 after many repeated reboots. Also do you know of anyone having luck patching their kernel with the 4.2 kernel I2S support?

[soren121]

It should work, yes. I've seen others complain about no sound in Fedora 22 and Ubuntu 15.04, but I've no clue why. It worked fine for me in Arch with the stock 4.0 kernel.

I don't know of anyone still actively working on a custom kernel with I2S for the XPS 13. Work on that seemingly ground to a halt after Dell fixed the BIOS with HDA mode. I did see Mario Limonciello (one of the Dell guys) reporting on the Linux ACPI mailing list a couple weeks ago that I2S was completely broken in 4.1. (4.2 is not in development yet.)

EDIT: To clarify, I2S is still being worked on upstream. I'm just saying that no one is working on a custom kernel that uses those upcoming patches.

[AdamDorwart]

Interesting. Also just an update for anyone else. I've managed to get sound working in Ubuntu 15.04 after numerous reboots. It appears the Audio device doesn't appear immediately after boot up. I just checked again after working for about an hour and now the device has magically appeared. For anyone else having this problem give the OS some time after a couple reboots and it should show up.

Really looking forward to this one getting resolved.

[jkayani]

Does anyone know what the status of this issue is? I'm currently running Ubuntu 16.04 and am considering setting up a Windows dual boot.

[soren121]

@jkayani Linux switched to I2S audio in kernel 4.4, which Ubuntu 16.04 ships with. You'll be fine.

[rdebeasi]

I'm running elementary OS 0.4 (based on Ubuntu 16.04), and I'm still experiencing this problem. Any suggestions?

Rebooting a few times after switching between Windows and Linux still fixes the problem, but I figured that as of kernel 4.4 I wouldn't have to do this. I'm on Windows 10, for what it's worth.