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obbe
1 Copper

Is Skylake working with multiple monitors for anyone?

Hi,

I now have two Skylake-based systems.

One is laptop XPS 15 9550 with QHD display. It seems to work fine under Fedora 23 with latest updated kernel as long as only using the internal panel. Connecting an external display (1920x1200) will trigger hard freeze (ping reply stops) immediately or within a few minutes. Drivers for the NVidia card is completely disabled so this is with just the i915 driver loaded.


The other is a Precision Tower 3620 with i7-6700 and only Intel graphics hardware present. Also using Fedora 23 with latest updated kernel seems to work fine as long as I only connect ONE display. Immediately when hotplugging a second display it will hard freeze.

Is anyone successfully using Skylake (and Skylake graphics) under Linux with multiple monitors?

12 Replies
aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

Oh, that's interesting.

I just ordered the windows version of the xps 13 skylake thinking that I would want to have fedora on it and not ubuntu.

Did you use the standard f23 installer to get the xps 15 working?

I was going to wipe the windows installation and do the f23 but now I'm concerned about using it with the TP15 dock or any external monitor.

obbe
1 Copper

RE: Is Skylake working with multiple monitors for anyone?

An update:

Summary: I made a breakthrough the other day and installation with Fedora 23 regular USB media works, and after upgrading all packages (brings in kernel 4.4.6) dual monitor setup also works and appears stable. This is with XPS15 and Precision T3620. Disclaimer: I haven't yet tried installing to the NVMe-drive on the XPS (used an external drive so far).

Also note that to simplify I've completely disabled the drivers for the NVidia graphics and have tested only with the Intel drivers so far.

I have no information on the TB15 dock but gather from the forums things are not great yet.

In more detail:

Fedora 23 installation experience: Installed using boot LiveCD from USB stick. It goes to the GRUB boot menu from the installation media, here you can select to start the Live environment. I got one line of text, then after a few seconds delay complaints from xhci_hcd. If I did nothing it would then launch the boot animation, but after a while drop out saying it can't find the root filesystem. For me, the trick was, immediately when the first xhci_hcd complaint is shown to rip out the USB stick and then promptly insert it again. Then it booted the live environment successfully. This was the same on both the XPS15 and the T3620.

In the live-boot I think the mouse was a bit jerky, but it worked well enough to perform the real installation at least. After booting to the installed environment you will have the 4.2 kernel which seems able to bring the system up, with at least basic graphics.

Since you bought the laptop with Windows you probably have to change SATA mode to AHCI in bios before Linux will see the internal drive.

The laptop (XPS15) was the first I got, in late January, with Windows. At that time, the 4.2 kernel didn't produce any useful and stable result with external monitor connected. I made an attempt with the 4.3 and possibly early 4.4 but it wasn't good. Switched to Intel's latest drm-intel-nightly which improved things slightly but was still very unstable as soon as I connected external monitors.

The Tower 3620 arrived just last week. I bought it with Ubuntu preinstalled (to show up in the statistics), but currently prefer Fedora, with the same installation experience as above. Fedora 23's most recent kernel was now 4.4.6 but it too didn't work for me, and drm-intel-nightly was also horrible. (It was stable with 1 monitor, but not with 2.)

Then the magic breakthrough arrived finally!  🙂  During a bit more systematic testing I discovered the distribution kernel 4.4.6 does actually work on both the laptop and the tower, with dual monitors, provided they are connected with HDMI or DisplayPort 1.1 (i.e. if I enable DP 1.2/MST in the monitor settings, all *** breaks loose). The monitors used are Dell U2415H, possibly you could get different results with different monitors. The drm-intel-nightly kernel was still unstable even with MST disabled.

For the laptop I've used the fixed HDMI port and also a USB-C-to-DP converter. Now with 4.4.6 I can actually plug both in at the same time so there are in total three displays connected and working.

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aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

Thanks for the update. I am more confident that I could get my current "f23 disk" run on the xps 13 I just ordered.

I'll try it as an external drive first. My current laptop is an older (16gb, 1tb) MBP 8,11. So the memory and disk config are identify of the new laptop. My current MBP is going flaky with the video card and audio port.

I was thinking of blowing away the windows disk (make a bare metal backup first) then try the f23 disk.

I order a new monitor and the TP15 as well.

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hardillb
1 Copper

RE: Is Skylake working with multiple monitors for anyone?

Did you mean the TP15 or the TB15? If you meant the TB15 then check out this forum post:

http://en.community.dell.com/techcenter/os-applications/f/4613/t/19678284

Sounds like support for either the USB-C or Thunderbolt docking stations is likely to be a month or 2 away yet.

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aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

I meant TP15. The newer thunderbolt one.

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aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

Obbe can you post your grub boot entry? I copied my 1TB SSD to the internal "hard drive" but it's not booting. Hanging at Reaching Target Basic System then fails to find the "root" disk. It's finding the EFI partition fine of course. I must not be loading soon grub driver that would allow it to find my root partition. My root partition is on LVM but specified by UUID. It looks like the internal hard disk disappears on me after loading the ram environment. It must be a driver of some sort that is not allowing the disk to seen at this point in the boot. I think I should get this to work fairly quickly once I figure out this boot issue. The fc23 live USB booted fine and on the first time.
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obbe
1 Copper

RE: Is Skylake working with multiple monitors for anyone?

Do you have nvme-attached storage and missing the nvme-driver from your initramfs? (This would be a kernel driver, not "grub driver".)


I'm currently redoing the laptop installation so don't have access to its grub configuration.

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aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

Well that could cause this issue. I'll look for it and load it in dracut and see if that helps.
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aappddeevv
2 Iron

RE: Is Skylake working with multiple monitors for anyone?

I regenerated the initramfs image on my old machine (using the SSD in the old machine whose image I just dd'd over to the xps13) using dracut and --add-modules nvme to include the proper driver then copied that to the nvme drive which is visible when booting the live fedora thumb drive. Then I rebooted and used grub to specify my special image via initramfs. That worked great. Looks like I am missing some BCM4350 wireless drivers as well.
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