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Serious screen flickering when WiFi is on (Dell XPS 15)
August 12, 2018
Edited: August 14, 2018
December 3, 2023
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i915.edp_vswing=2 kernel parameter
Although OP has solved the problem thanks to Arch Linux link in next section questions still remain about what it means.
From announcement: Display Port Presentation December 2010:
- Embedded DisplayPort (eDP) was developed to be used specifically in embedded display applications
- Notebook, Netbook, and Notepad PCs
- It is designed to replay LVDS technology
As many people here already know,
i915 is Intel’s display driver for Linux that has been around for decades.
vswing component I cannot fathom but, you can find the C code that controls it here: https://patchwork.kernel.org/patch/6349211/
The parameter settings (after
= sign) can be:
0=default, to do nothing
1=not sure, haven’t found answer yet
2=control flicker, which OP used
I will set my kernel parameter to
1 and reboot after posting this answer.
This is a temporary setting for older kernels according to what I read tonight. So you should occasionally remove the setting after new kernels are installed to see if it’s still necessary.
Finally there is an interesting tidbit here: https://patchwork.kernel.org/patch/9303023/
- FIXME On Dell XPS 13 9350 the OpRegion panel type (0) gives us
- low vswing for eDP, whereas the VBT panel type (2) gives us normal
- vswing instead. Low vswing results in some display flickers, so
- let’s simply ignore the OpRegion panel type on SKL for now.
- FIXME On Dell XPS 13 9350 and Dell XPS 13 L322X the
- OpRegion panel type (0) gives us low vswing for eDP,
- whereas the VBT panel type (2) gives us normal vswing
- instead. Low vswing results in some display flickers, so
- let’s simply ignore the OpRegion panel type on SKL and
- IVYBRIDGE for now. */
Original post that helped OP stumble on solution
Here is a great link for you: Arch Linux Dell XPS 13 (9350):
Content adaptive brightness control
In the XPS 13 the display panels (both FHD and QHD+) come with
adaptive brightness embedded in the panel firmware, this “content
adaptive brightness control” (usually referred to as CABC or DBC) will
adjust the screen brightness depending on the content displayed on the
screen and will generally be found undesirable, especially for Linux
users who are likely to be switching between dark and light screen
content. Dell has issued a fix for this however it is only available
to run in Windows and for the QHD+ model of the laptop so this
precaution should be taken before installing Linux, the FHD model of
the XPS 13 (9350) cannot be fixed. This is not a problem with the
panel but rather a problem with the way the panels are configured for
the XPS 13, as the same panel exists in the Dell’s Latitude 13 7000
series (e7370) FHD model but with CABC disabled. The fix is available
directly from Dell.
Additionally check these posts from other Dell users: