Ubuntu 16.04 on Dell Xps 15 9550 (i7-6700HQ - 1TB SSD - UHD 4k touch)

[morhook]

Someone has reported the brightness 4K problem with Bios 1.2.10 on Dell forum http://en.community.dell.com/techcen...27410#20927410

[rockorequin]

Someone has reported the brightness 4K problem with Bios 1.2.10 on Dell forum http://en.community.dell.com/techcen...27410#20927410

That post didn't sound very hopeful (they said they had referred it to Canonical, when it's clearly a BIOS regression!) but Dell confirmed to me separately that they are aware of the issue and are "continuing to investigate how to resolve" it.

FYI, I had two other issues in the meantime:

1. The headphones weren't working at all. I fixed this in alsamixer by un-muting the first headphone output (MM was displayed at the bottom of the column; selecting the column and pressing M toggled the mute. Note that it doesn't auto-unmute if you just change the volume). I also get the same problem as others have mentioned, where sometimes it only detects the HDMI audio output; clearing the contents of ~/.config/pulseaudio/ and issueing "pulseaudio -k" fixes this.

2. The laptop was rebooting on resume (it's really annoying if you lose work that way!). It did almost the same thing in Windows, too - I just got a black screen on resume and CTRL-ALT-DEL did a reboot. I fixed it by changing the BIOS settings (still on 1.2.0 because of the 4K brightness issue). I reset the BIOS settings to default, changed the disk back to AHCI and reconstructed my Ubuntu boot, set POST behaviour back to minimal (or it takes longer to boot), and I also enabled USB recharging during sleep. I suspect that last one might have been the key. The way the laptop was behaving, it was as if it lost its RAM contents during sleep, so maybe the BIOS was disconnecting the battery completely.

[betterwithchemistr]

A new BIOS is available (1.2.13, http://www.dell.com/support/home/it/...&categoryId=BI).
Have anyone already tried it?

[bgcngm]

A new BIOS is available (1.2.13, http://www.dell.com/support/home/it/...&categoryId=BI).
Have anyone already tried it?

Yeah, I did and the brightness issue is still there. :/

[betterwithchemistr]

Yeah, I did and the brightness issue is still there. :/

I don't have the brightness issue (4K display) but the computer still fails on resume (although it seems a bit random... sometimes it fails, sometimes it wakes up normally...)

[ckam032]

Hey guys, I was wondering if there are any tweaks you can do to the intel card? I've been using Nvidia because on intel, animations are choppy in every distro I've tried.

[rockorequin]

I don't have the brightness issue (4K display) but the computer still fails on resume (although it seems a bit random... sometimes it fails, sometimes it wakes up normally...)

Just checking, did you try what I mentioned in a post above? I reset the BIOS settings to default, changed the disk back to AHCI and reconstructed my Ubuntu boot, set POST behaviour back to minimal (or it takes longer to boot), and I also enabled USB recharging during sleep. Do you have that last one set?

[2iii7]

I have BIOS 1.2.13 on i5 FHD. Problems so far:
When suspending on AC by closing the lid the computer goes to sleep for a sec, then resumes. When suspending from the power menu again the computer suspends and stays suspended and can be resumed. On battery suspend is working fine by closing the lid.
Brightness control has 12 steps on that version.

[rockorequin]

I just tested BIOS 1.2.13 and I still have the brightness problem after resume (there is only 100% brightness or screen off).

Just to clarify an earlier comment I made about about the setting for supplying power during sleep, it's in BIOS System Configuration and it's called USB Powershare (it supplies power even when the PC is off).

[betterwithchemistr]

Just checking, did you try what I mentioned in a post above? I reset the BIOS settings to default, changed the disk back to AHCI and reconstructed my Ubuntu boot, set POST behaviour back to minimal (or it takes longer to boot), and I also enabled USB recharging during sleep. Do you have that last one set?

Hi, I didn't try what you mentioned above, but I have the USB Powershare enabled: the strange thing is that when the PC is turned off or in sleep, if I plug something in the usb port (e.g. the cellphone) it doesn't work. With the previous version of the bios I had (the last one before the 1.2.0 version.. maybe 1.1.19?) it worked.

I'll give a try to what you mentioned above in a few days, I don't have time right now

Thank you

-- EDIT --

Hi, now I tried what you mentioned, I've noticed that:
when I'm on Linux (Ubuntu GNOME) and put the pc to sleep and reopen the lid, the screen remains black, but if I type my password to unlock it and press enter, then when I increase the luminosity (f12 key) the screen turns on, but the luminosity level is stuck to maximum;
when I'm on Windows (Win 10) the pc wakes up normally after I put it in sleep mode (and the luminosity level is not stuck).

Also, USB Powershare is enabled in BIOS, and if I connect via usb the cellphone when the pc is on it starts charging normally, but when I close the lid the phone stops charging (both in linux and windows).

Hope this helps