Thread (5 messages) 5 messages, 4 authors, 2017-01-29

Re: [PATCH 2/6] wl1251: Use request_firmware_prefer_user() for loading NVS calibration data

From: Kalle Valo <hidden>
Date: 2017-01-27 12:29:13
Also in: linux-wireless, lkml

Pali Rohár [off-list ref] writes:
On Friday 27 January 2017 13:49:03 Kalle Valo wrote:
quoted
Pali Rohár [off-list ref] writes:
quoted
quoted
So
for those other platforms there will be a delay waiting for user-mode
helper to fail, before trying to get nvs file from /lib/firmware.
Yes, there will be. But there is no easy way to fix this problem that
kernel is trying to use default/example NVS data...
Kernel is doing correctly and requesting NVS data as expected, the
problem here is that linux-firmware claims that the example NVS data is
real calibration data (which it is not). Distros should not use that,
only developers for testing purposes. We should not courage users using
example calibration data.

The simple fix is to rename the NVS file in linux-firmware to something
like wl1251-nvs.bin.example, no need to workaround this in kernel. If
you send a patch to linux-firmware I'm happy to ack that.
I agree with rename and fact that default/example data should not be
used.

But...

1) Kernel should not read device/model specific data from VFS where
are stored not-device-specific files preinstalled by linux
distributions.

And linux distributions are already putting files into VFS and kernel
cannot enforce userspace to not do that (as they are already doing it).
I'm having problems to understand what you are saying here.
2) It was already tested that example NVS data can be used for N900 e.g.
for SSH connection. If real correct data are not available it is better
to use at least those example (and probably log warning message) so user
can connect via SSH and start investigating where is problem.
I disagree. Allowing default calibration data to be used can be
unnoticed by user and left her wondering why wifi works so badly.
3) If we do rename *now* we will totally break wifi support on Nokia
N900.
Then the distro should fix that when updating the linux-firmware
packages. Can you provide details about the setup, what distro etc?

-- 
Kalle Valo
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