FS#49623 - [linux] 4.6.x slow QT4 text input

Attached to Project: Arch Linux
Opened by Marco Kundt (flexo3001) - Wednesday, 08 June 2016, 14:59 GMT
Last edited by Toolybird (Toolybird) - Saturday, 27 May 2023, 07:23 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Tobias Powalowski (tpowa)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 2
Private No

Details

Description:
Since Linux 4.6 i have a really bad input rate in QT4 text input boxes. I got those bug inside all Virtualbox input boxes (VM-window as well) and inside keepassx2. Everything else seems to work as aspected inside those applications.


Additional info:
* linux-4.6.1-2 and linux-4.6.2-1
* qt4-4.8.7-9


Steps to reproduce:
Install new kernel and use QT4 applications.
This task depends upon

Closed by  Toolybird (Toolybird)
Saturday, 27 May 2023, 07:23 GMT
Reason for closing:  No response
Additional comments about closing:  Plus it's old and stale. Assuming fixed by now. If not, please report upstream.
Comment by Gaetan Bisson (vesath) - Wednesday, 08 June 2016, 19:26 GMT
Same as  FS#49431  except the package is now in [core]...
Comment by Gaetan Bisson (vesath) - Wednesday, 08 June 2016, 19:29 GMT
Marco, could you confirm that qt5 apps are also affected?
Comment by Tobias Powalowski (tpowa) - Wednesday, 08 June 2016, 19:39 GMT
Please try disabling PSR extension if you are using intel graphic hardware.
Comment by Marco Kundt (flexo3001) - Wednesday, 08 June 2016, 19:42 GMT
Yes, QT5 seems to affected as well. I tried inside Qutebrowser but here it seems to be something related to cursor rate. It blinks every ~2s and then all the characters typed in appears at the next blink.
Comment by Gaetan Bisson (vesath) - Wednesday, 08 June 2016, 20:20 GMT
Unfortunately disabling PSR does not work for me.
Comment by Marco Kundt (flexo3001) - Wednesday, 08 June 2016, 20:25 GMT
It isn't working on my machine (Thinkpad X240 w/ Intel graphics) too.
Comment by Gaetan Bisson (vesath) - Wednesday, 08 June 2016, 20:34 GMT
For me it's a macbook pro, intel Broadwell-U graphics.
Comment by Gaetan Bisson (vesath) - Friday, 10 June 2016, 08:21 GMT
So the issue is with framebuffer compression. Disabling it (e.g. add i915.enable_fbc=0 as kernel boot parameter) fixes it with linux-4.6.
Comment by Marco Kundt (flexo3001) - Friday, 10 June 2016, 08:27 GMT
You are right. It fixes the problems for me. But strange enough that only QT is affected.
Comment by jb (jb.1234abcd) - Friday, 10 June 2016, 12:04 GMT
We have the same problem (typing and scrolling delay) reported in web browsers (Opera, Firefox), VirtualBox, Skype.
Fallback of linux kernel 4.5.x or corresponding apps fixed the problem.
Your i915.enable_fbc=0 fixes it for recent versions.

I would suggest changing report title and increasing the severity of this problem to high/critical.
Comment by Marco Kundt (flexo3001) - Friday, 10 June 2016, 13:07 GMT
You are right. It fixes the problems for me. But strange enough that only QT is affected.
Comment by Jan de Groot (JGC) - Friday, 10 June 2016, 13:31 GMT
This is probably https://bugreports.qt.io/browse/QTBUG-50313, but upstream closed it as it's filed against an outdated version.
Comment by Marco Kundt (flexo3001) - Saturday, 11 June 2016, 16:20 GMT
You are right. It fixes the problems for me. But strange enough that only QT is affected.
Comment by Manuel Groß (mgr) - Monday, 20 June 2016, 22:12 GMT
I have this issue, too. For me, sakura (GTK) and sublime (custom UI toolkit) are affected. I didn't check keepassx2 though.
Downgrading linux to 4.5 or disabling fbc fixes those as well.
I'm using a Thinkpad x250 with Intel graphics.
For reference: https://lists.archlinux.org/pipermail/arch-general/2016-June/041473.html
Comment by Gaëtan Harter (cladmi) - Tuesday, 21 June 2016, 07:48 GMT
Same issue for me, with a thinkpad t44p and intel graphics, disabling fbc or using lts fixes these.
I saw the issue with firefox and gnome-terminal.

I tested with gnome-terminal to type 'date\n' many times.
When typing 'date' without enter it would get stuck randomly after 1-2 characters, and then show show the remaining after 1 to 5 seconds.
When typing 'date\n', it would display the full output when typing enter.
Comment by Manuel Groß (mgr) - Thursday, 23 June 2016, 23:00 GMT
May the issue be a result of turning fbc on by default in the 4.6 kernel? Do we all have Intel graphics?
https://www.phoronix.com/scan.php?page=news_item&px=Intel-DRM-Next-PSR-FBC
Comment by Bruno Pagani (ArchangeGabriel) - Thursday, 23 June 2016, 23:19 GMT
@mgr: Yes, it is. That’s known for sure, the question is whether one of you did report this upstream against the kernel DRM module. I’m not affected personally, so I can’t.
Comment by Manuel Groß (mgr) - Friday, 24 June 2016, 01:27 GMT
@ArchangeGabriel Oh, okay. The exact problem wasn't clear to me. I don't know, if the Intel guys use the kernel bugtracker, so I sent a mail to the intel-gfx mailing list.
https://lists.freedesktop.org/archives/intel-gfx/2016-June/099268.html
Comment by mattia (nTia89) - Sunday, 27 February 2022, 11:22 GMT
I cannot reproduce the issue. Is it still valid for you?

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