Wifi slow on the XPS13 (9360) (QCA6174) (Was Re: ath10k-regression in 4.14: Connections aborts with "failed to extract amsdu: -11")

[Thorsten Leemhuis]

Lo! Splitting this thread to focus on a issue that has nothing to do
with the regression in 4.14 I reported:

On 03.10.2017 01:40, Ryan Hsu wrote:
> On 10/01/2017 01:59 AM, Thorsten Leemhuis wrote:
>>> ath10k_pci 0000:3a:00.0: Direct firmware load for ath10k/pre-cal-pci-0000:3a:00.0.bin failed with error -2
>>> ath10k_pci 0000:3a:00.0: Direct firmware load for ath10k/cal-pci-0000:3a:00.0.bin failed with error -2
>> Do they have anything to do with this? Hardware is
> This error message is confusing since QCA6174 is not supporting
> pre-calibration feature, this reminds me that we need to clean this up.

I guess that would be good to avoid confusion. But while at it: If you
have a minute, could you please explain to me how to properly set up the
wifi firmware files for my Dell XPS13 (9360)? The reasons why I'm
asking: Sending data via wifi is really slow on my laptop (scp copies
only get 2 to 5 MByte/s on networks that are known to be a lot faster).
I wonder if the firmware files or the calibration data is part of the
reason wifi Tx is slow. The machine is normally shipped with a slightly
enhanced Ubuntu 16.04. That among others contains a package with the
machine specific files board.bin and board-2.bin that replace the files
normally installed in /lib/firmware/ath10k/QCA6174/hw3.0/ Are those
machine specific files crucial to have or are the one from the
linux-firmware repo good enoguh? I'm using Fedora and could copy the
ones from Ubuntu over, but obviously they will get overwritten every
time Fedora ships a new linux-firmware package – IOW: every few weeks :-/

Side note: You find a lot of reports about slow wifi is you search the
net with terms like "9360 wifi slow linux". Ubuntu fixed that a few
months ago with this patch:
http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/commit/?id=9690f19f07fee2acb2b04ea5eaa5db184ee175d5

Some bugs about this:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1692836
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670041

But from what I gathered by searching the net and asking on #ath10k I
got the impression that patch is a massive ugly hack and no way
acceptable upstream.  Is that correct? If yes: is there maybe a proper
fix out there somewhere?

Ciao, Thorsten