netdev - r8169 driver causing screen flickering since commit a99790bf5c7f3d68d8b01e015d3212a98ee7bd57

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Date:   Fri, 15 Feb 2019 11:44:08 +0100
From:   Elias Rydberg <rydberg1995@...il.com>
To:     netdev@...r.kernel.org
Subject: r8169 driver causing screen flickering since commit
 a99790bf5c7f3d68d8b01e015d3212a98ee7bd57

Hi,

Since commit a99790bf5c7f3d68d8b01e015d3212a98ee7bd57, some systems have 
experienced screen flickering, followed by a black screen, when using 
WiFi (for example starting NetworkManager). So far this only seems to be 
a problem with the following spec:

CPU: Intel i7-8550U
WiFi module: Intel AC-9260 1730Mbps

I contacted the author of the commit and got the following reply:

"From platforms I’ve seen, if ASPM on r8169 is disabled, the deepest 
Package C-State on Intel CPU will limit to PC3.

If the ASPM on r8169 is enabled, it can reach to PC8 when the display is 
on, and be able to reach PC10 when display is off.

So the issue seems to be a platform bug - deeper Package C state makes 
your system unstable.

Please contact the system vendor, the deepest Package C state can be 
reach should be set by BIOS."

Now, Kai-Heng suggest contacting the system vendor, but after consulting 
my distributions forum, I got the suggestion of contacting this email 
list in hope of implementing a patch disabling the ASPM in the r8169 in 
systems with this spec. I apologize if this is a completely unreasonable 
request; I'm not experienced with kernel developing.

Kind regards,
Elias Rydberg

Thread in my distributions forum, which includes more information:
https://bbs.archlinux.org/viewtopic.php?id=244115 
<https://bbs.archlinux.org/viewtopic.php?id=244115>

The result of a kernel bisection I did:

|a99790bf5c7f3d68d8b01e015d3212a98ee7bd57 is the first bad commit commit 
a99790bf5c7f3d68d8b01e015d3212a98ee7bd57 Author: Kai-Heng Feng 
<kai.heng.feng@...onical.com <mailto:kai.heng.feng@...onical.com>> Date: 
Thu Jun 21 16:30:39 2018 +0800 r8169: Reinstate ASPM Support On Intel 
platforms (Skylake and newer), ASPM support in r8169 is the last missing 
puzzle to let CPU's Package C-State reaches PC8. Without ASPM support, 
the CPU cannot reach beyond PC3. PC8 can save additional ~3W in 
comparison with PC3 on a Coffee Lake platform, Dell G3 3779. This is 
based on the work from Chunhao Lin <hau@...ltek.com 
<mailto:hau@...ltek.com>>. Signed-off-by: Kai-Heng Feng 
<kai.heng.feng@...onical.com <mailto:kai.heng.feng@...onical.com>> 
Signed-off-by: David S. Miller <davem@...emloft.net 
<mailto:davem@...emloft.net>> :040000 040000 
87d4515c14f8eb8cf99b6f47f97ca4db700931c1 
e542595c74609136a7094777afb10b83012f6643 M drivers|