linux-kernel - Re: [PATCH 2/6] wl1251: Use request_firmware_prefer

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Message-Id: <201701301903.02043@pali>
Date:   Mon, 30 Jan 2017 19:03:01 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Pavel Machek <pavel@....cz>, Kalle Valo <kvalo@...eaurora.org>,
        Arend Van Spriel <arend.vanspriel@...adcom.com>,
        Ming Lei <ming.lei@...onical.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        David Gnedt <david.gnedt@...izone.at>,
        Michal Kazior <michal.kazior@...to.com>,
        Daniel Wagner <wagi@...om.org>,
        Sebastian Reichel <sre@...nel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Grazvydas Ignotas <notasas@...il.com>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 2/6] wl1251: Use request_firmware_prefer_user() for loading NVS calibration data

On Monday 30 January 2017 18:53:09 Tony Lindgren wrote:
> * Pavel Machek <pavel@....cz> [170127 11:41]:
> > On Fri 2017-01-27 17:23:07, Kalle Valo wrote:
> > > Pali Rohár <pali.rohar@...il.com> writes:
> > > > On Friday 27 January 2017 14:26:22 Kalle Valo wrote:
> > > >> Pali Rohár <pali.rohar@...il.com> writes:
> > > >> > 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.
> > > > 
> > > > So there are only two options:
> > > > 
> > > > 1) Disallow it and so these users will have non-working wifi.
> > > > 
> > > > 2) Allow those data to be used as fallback mechanism.
> > > > 
> > > > And personally I'm against 1) because it will break wifi
> > > > support for *all* Nokia N900 devices right now.
> > > 
> > > All two of them? :)
> > 
> > Umm. You clearly want a flock of angry penguins at your doorsteps
> > :-).
> 
> Well this silly issue of symlinking and renaming nvs files in a
> standard Linux distro was also hitting me on various devices with
> wl12xx/wl18xx trying to use the same rootfs.

wl12xx/wl18xx have probably exactly same problem as wl1251.

> Why don't we just set a custom compatible property for n900 that then
> picks up some other nvs file instead of the default?

But that still does not solve this problem correctly. Every n900 device 
have different NVS file. If we allow to load firmware directly from VFS 
without userspace helper we would see again same problem.

-- 
Pali Rohár
pali.rohar@...il.com

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