pmdevita/Readme.md

## Readme.md

      
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    BCM4350/DW1820A/XPS 9350 Wi-Fi Fix

If you are using a BCM4350/DW1820A Wi-Fi card or an XPS 13 9350 on Linux, you may have run into an issue where your Wi-Fi
stops working after suspension/sleep. Hopefully my hours of research can help you.
The Problem

It appears there is some kind of power management problem with this card. There are several different threads documenting
these issues (I'll link them below). These issues were officially resolved sometime around kernel 4.19 but I'm still
experiencing them and I imagine some other people might be too.
For me, most times when my laptop goes to sleep, it resumes with the wi-fi in a strange broken state. It doesn't respond
and it can't search for networks. Rebooting straight into Windows creates a blue screen and rebooting straight to Mac
(hackintosh gang) results in funny business with the wi-fi as well. Sometimes the only solution is to completely turn
off the computer and then turn it back on.
Look through the linked threads if you want more details. I'm just going to give the solution here. It's a bit of a hack but
it's 99% close enough.
The Solution

Unload the brcmfmac kernel module before sleep and load it back up after sleep. It adds a couple seconds extra to getting
wi-fi back on after resuming but otherwise acts normal. Unfortunately, this only fixes Wi-Fi in Linux for me, rebooting
to other OSes still causes the aforemented issues. The solution is to shutdown first, not reboot.
Copy these two services into your /etc/systemd/system folder and then run
sudo systemctl enable wifi-before-sleep.service
sudo systemctl enable wifi-after-sleep.service
From there you should be good to go.
The New Problem

So I'm not sure if this was there before but after I started using these services I started getting a weird problem where the wifi drivers would, at random, crash so bad, the computer would be unable to sleep or even shutdown and restart, requiring a hard reset. I think the only resolution we're really going to see from this is if the kernel devs patch the wifi drivers.
Threads about the problem

https://bugs.launchpad.net/ubuntu/+source/broadcom-sta/+bug/1765036

https://bbs.archlinux.org/viewtopic.php?id=242382

https://bugzilla.kernel.org/show_bug.cgi?id=201853

https://bugs.archlinux.org/task/60832

  
## wifi-after-sleep.service
[Unit]
Description=Enable wifi after sleep so it doesn't freak out
After=suspend.target

[Service]
ExecStart=/usr/bin/modprobe brcmfmac

[Install]
WantedBy=suspend.target

## wifi-before-sleep.service
[Unit]
Description=Disable wifi before sleep so it doesn't freak out
Before=suspend.target

[Service]
ExecStart=/usr/bin/rmmod brcmfmac

[Install]
WantedBy=suspend.target
	[Unit]
	Description=Enable wifi after sleep so it doesn't freak out
	After=suspend.target

	[Service]
	ExecStart=/usr/bin/modprobe brcmfmac

	[Install]
	WantedBy=suspend.target
	[Unit]
	Description=Disable wifi before sleep so it doesn't freak out
	Before=suspend.target

	[Service]
	ExecStart=/usr/bin/rmmod brcmfmac

	[Install]
	WantedBy=suspend.target