Do you know how to troubleshoot a laptop touchscreen from afar?
February 7, 2021 12:49 PM Subscribe
I have a newish-to-me HP Elitebook 2760p with Ubuntu on it. The touchscreen was working earlier today and it has stopped working. it doesn't recognize my touch or the stylus at all. I know nothing other than how to find the terminal. Please hold my hand and help me fix this problem. Thanks!
You can probably do a bit of troubleshooting before deciding it's definitely a hardware problem.
'dmesg' is a good place to look for errors and interesting warnings. so something like this might be a good place to start poking, replacing 'touch' with various other bits of text that might relate to the touchscreen input:
dmesg | grep -i touch
You can read input events directly into the terminal by poking around and 'cat'ing things in /dev/input. If you see a device there that looks like the right thing, you can do:
cat /dev/input/thingamabob
and then touch the screen a bunch and see if you get interesting goop coming through to your terminal. If you do, it's probably a driver problem, not a hardware problem. If the device doesn't show up in inputs, it may be a driver problem as well. Devices also often show up in lsusb or lspci; it can be good to check if it shows up there.
If it doesn't show up in /any/ of these places, I would start to suspect a hardware problem.
posted by kaibutsu at 3:16 PM on February 7, 2021
'dmesg' is a good place to look for errors and interesting warnings. so something like this might be a good place to start poking, replacing 'touch' with various other bits of text that might relate to the touchscreen input:
dmesg | grep -i touch
You can read input events directly into the terminal by poking around and 'cat'ing things in /dev/input. If you see a device there that looks like the right thing, you can do:
cat /dev/input/thingamabob
and then touch the screen a bunch and see if you get interesting goop coming through to your terminal. If you do, it's probably a driver problem, not a hardware problem. If the device doesn't show up in inputs, it may be a driver problem as well. Devices also often show up in lsusb or lspci; it can be good to check if it shows up there.
If it doesn't show up in /any/ of these places, I would start to suspect a hardware problem.
posted by kaibutsu at 3:16 PM on February 7, 2021
Response by poster: It told me
dmesg: read kernel buffer failed: Operation not permitted
posted by aniola at 3:28 PM on February 7, 2021
dmesg: read kernel buffer failed: Operation not permitted
posted by aniola at 3:28 PM on February 7, 2021
Best answer: dmesg is root-only, you'll have to sudo.
Did you reboot between it working and not? Updates?
Try:
https://ubuntuforums.org/showthread.php?t=2252099
https://bugs.launchpad.net/ubuntu/+source/xf86-input-wacom/+bug/1392887
posted by rhizome at 3:48 PM on February 7, 2021 [1 favorite]
Did you reboot between it working and not? Updates?
Try:
- grep EE /var/log/Xorg.0.log
- grep -i Wacom /var/log/{Xorg.0.log,messages,daemon.log}|less (spacebar to page down, 'u' to go up)
https://ubuntuforums.org/showthread.php?t=2252099
https://bugs.launchpad.net/ubuntu/+source/xf86-input-wacom/+bug/1392887
posted by rhizome at 3:48 PM on February 7, 2021 [1 favorite]
Response by poster: I restarted the computer and now it works. Is there some sort of keyboard shortcut that I accidentally hit that I should know about?
posted by aniola at 3:49 PM on February 7, 2021
posted by aniola at 3:49 PM on February 7, 2021
If the driver crashed you would probably need a reboot to recover. My experience with HP and Linux has been bad over several machines, HP simply does not support Linux well.
posted by COD at 5:35 PM on February 7, 2021
posted by COD at 5:35 PM on February 7, 2021
If your computer went to hibernate or suspend, the driver didn't load correctly on resume. Happens to many touch drivers. It's relatively computer dependent, but I had this issue on last two touch screen laptops with Ubuntu.
posted by Yavsy at 8:10 PM on February 7, 2021 [1 favorite]
posted by Yavsy at 8:10 PM on February 7, 2021 [1 favorite]
If you restarted and it's working now, it's possible the driver just "crashed". It's much rarer in *nix platforms, but it does happen occasionally.
posted by kschang at 7:59 AM on February 8, 2021
posted by kschang at 7:59 AM on February 8, 2021
Fwiw, lots of processes in Linux can be restarted from the command line if you're able to figure out the right incantation; typically they're the same way the OS loads them when booting up. And once you know the incantation, there's likely a script that runs automatically when waking from hibernation that the incantation can be put in, to run automatically. (Search terms might include 'udev'.)
It's been a long time since I've poked around these particular corners, though. The usual trade-off for Linux is a bit more jankiness, but once you learn a bit of where to look for problems, there's a good chance you can solve it with a bit of duct tape (or, shell scripting).
posted by kaibutsu at 9:00 AM on February 8, 2021 [1 favorite]
It's been a long time since I've poked around these particular corners, though. The usual trade-off for Linux is a bit more jankiness, but once you learn a bit of where to look for problems, there's a good chance you can solve it with a bit of duct tape (or, shell scripting).
posted by kaibutsu at 9:00 AM on February 8, 2021 [1 favorite]
Response by poster: Poking around is above my current skill level- what do I type after typing udev? (This happened again already, and I'm really hoping I didn't pay extra for a touchscreen computer that has decided not to touchscreen half the time.)
posted by aniola at 1:05 PM on February 10, 2021
posted by aniola at 1:05 PM on February 10, 2021
A little Google brought up this VERY old topic on StackExchange
posted by kschang at 3:35 AM on February 12, 2021
posted by kschang at 3:35 AM on February 12, 2021
This thread is closed to new comments.
You may have dislodged or damaged one of the cables that runs through the twisty hinge thing to the display. If you're not happy taking laptops, phones and other gadgets apart, then your best option is probably to find a local PC repair place to take a look at it.
posted by pipeski at 2:04 PM on February 7, 2021