Mouse pointer flickers when --scale is applied via xrandr

Submitted by Thilo-Alexander Ginkel

Assigned to Xorg Project Team

Link to original bug (#101225)

Description

Created attachment 131562 dmesg

Hi there,

as discussed with mupuf on #intel-gfx yesterday I am getting an ugly mouse pointer flickering after installing Linux (KDE/Plasma 5.9) on my new ThinkPad T470p (Kaby Lake, HD Graphics 630, Nvidia graphics disabled via ACPI, modesetting). I have three monitors attached (one built-in HiDPI screen, two external ones). I have been able to track down the screen flicker to using --scale 0.75x0.75 on eDP-1 (the internal screen) via xrandr (I need to apply some screen-specific scaling due to the two external screens being normal DPI and the internal one being HiDPI).

I am using Arch Linux and hit the issue on both the regular Kernel 4.11.2 and the LTS Kernel 4.9.30.

$ uname -a Linux vega 4.11.2-1-ARCH #1 (closed) SMP PREEMPT Mon May 22 06:53:49 CEST 2017 x86_64 GNU/Linux

Linux distribution: Arch Linux (x86_64)

Machine or mother board model: Lenovo ThinkPad T470p (i7-7820HQ)

Display connector: 1x eDP (2560x1440 internal 14" screen) 2x DP (2560x1440 external 25" screens connected via Lenovo Ultra Dock)

Video recording of flicker: https://goo.gl/photos/E1aspC36Zs967sUV6

dmesg output and Xorg log attached.

xrandr command line: -- 8< -- /usr/bin/xrandr -d :0.0 --output DP-3-2 --mode 2560x1440 --pos 0x0 --rotate normal --primary --output DP-3-1 --mode 2560x1440 --pos 2560x0 --rotate normal --output eDP-1 --mode 2560x1440 --pos 5120x774 --rotate normal --scale 0.75x0.75 -- 8< --

Please let me know if you need any further details.

Thanks, Thilo

Attachment 131562, "dmesg":
dmesg-4.11.2-1-ARCH