Why doesn't my laptop work with my monitor on certain kernels?

asked 2016-12-09 03:43:28 -0500

rumbles gravatar image

updated 2016-12-09 03:55:39 -0500

I'm using a Lenovo T550 laptop, which comes with:

Intel(R) HD Graphics 5500 (Broadwell GT2)
Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz

At work I have a Dell U2913WM monitor, I connect this to the Lenovo 550 through the display port. The display is not without issues, which I have asked about here but generally the fact the screen doesn't always wake up is an annoyance, I can work around that.

However, using F24, I was unable to get the monitor to work at all with any kernel after 4.8.4. When you connect the monitor to the laptop it doesn't detect the monitor is connected and then after a few minutes the laptop stops responding. I tried using a Live USB with one of the problematic kernels on Fedora 24 and it seemed to work fine.

I was then advised to try connecting the monitor to my laptop while it was off and powering it on with it connected. I tried this on Fedora 25 (which I have installed on a second SSD which I can swap in when needed) which only had the OS installed on an encrypted disk, updated and a handful of applications installed from the normal repos sysinfo

When I tried this with the default kernel for F25 it worked fine, the monitor came on after I entered the encryption password (although in F24 it comes on when the password prompt appears). But when I tried on the newer 4.8.11 kernel on F25 the laptop hung when the Fedora icon had finished loading before the login screen came on, it seemed to get stuck as the monitor was waking up, as it came out of power saving mode just as the laptop hung.

It's worth noting, I have another monitor at home (Acer X34A) that I can connect to the display port mini port on my laptop and, even on kernels where I have experienced hangs every time when connecting to my work monitor, the connection comes up immediately and I have no issues.

Any suggestions on how to investigate further are welcome, I'm not sure at this point what else I can try...

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I too had such problems with my laptop "Dell XPS 15 L502", with F24. In my case, it was the problem with my graphics card drivers. F25 with 4.8.11 is much better.

Are you sure the problem dependence on your kernel version ? F25 comes with wayland instead of X server..!

warlock20 gravatar imagewarlock20 ( 2016-12-12 17:40:21 -0500 )edit

I've had the issue on F24 and F25, so nothing to do with Wayland as far as I know.

I don't have any issues on 4.8.4-200-fc24, but all the subsequent kernels cause a system hang when I connect that monitor to my laptop. The same with F25, the first kernel that was installed from the live disk gave me no issues, the kernel that came out last week caused system hangs

rumbles gravatar imagerumbles ( 2016-12-16 06:48:54 -0500 )edit