From: Pali =?utf-8?q?Roh=C3=A1r?= <pali.rohar@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 2/6] wl1251: Use request_firmware_prefer_user() for loading NVS calibration data
Date: Mon, 26 Dec 2016 17:04:56 +0100
Cc: Arend Van Spriel <arend.vanspriel@broadcom.com>,
        Ming Lei <ming.lei@canonical.com>,
        "Luis R. Rodriguez" <mcgrof@kernel.org>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        Kalle Valo <kvalo@codeaurora.org>,
        David Gnedt <david.gnedt@davizone.at>,
        Michal Kazior <michal.kazior@tieto.com>,
        Daniel Wagner <wagi@monom.org>,
        Tony Lindgren <tony@atomide.com>,
        Sebastian Reichel <sre@kernel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        Grazvydas Ignotas <notasas@gmail.com>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org
References: <1482598381-16513-1-git-send-email-pali.rohar@gmail.com> <201612252146.44496@pali> <20161226154353.GA27087@amd>
In-Reply-To: <20161226154353.GA27087@amd>
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On Monday 26 December 2016 16:43:53 Pavel Machek wrote:
> Hi!
>=20
> > > > NVS calibration data for wl1251 are model specific. Every one
> > > > device with wl1251 chip has different and calibrated in
> > > > factory.
> > > >=20
> > > > Not all wl1251 chips have own EEPROM where are calibration data
> > > > stored. And in that case there is no "standard" place. Every
> > > > device has stored them on different place (some in rootfs file,
> > > > some in dedicated nand partition, some in another proprietary
> > > > structure).
> > > >=20
> > > > Kernel wl1251 driver cannot support every one different storage
> > > > decided by device manufacture so it will use
> > > > request_firmware_prefer_user() call for loading NVS calibration
> > > > data and userspace helper will be responsible to prepare
> > > > correct data.
> > >=20
> > > Responding to this patch as it provides a lot of context to
> > > discuss. As you might have gathered from earlier discussions I
> > > am not a fan of using user-space helper. I can agree that the
> > > kernel driver, wl1251 in this case, should be agnostic to
> > > platform specific details regarding storage solutions and the
> > > firmware api should hide that. However, it seems your only
> > > solution is adding user-space to the mix and changing the api
> > > towards that. Can we solve it without user-space help?
> >=20
> > Without userspace helper it means that userspace helper code must
> > be integrated into kernel.
> >=20
> > So what is userspace helper doing?
> >=20
> > 1) Read MAC address from CAL
> > 2) Read NVS data from CAL
> > 3) Modify MAC address in memory NVS data (new for this patch
> > series) 4) Modify in memory NVS data if we in FCC country
> >=20
> > Checking for country is done via dbus call to either Maemo cellular
> > daemon or alternatively via REGDOMAIN in /etc/default/crda. I have
> > plan to use ofono (instead Maemo cellular daemon) too...
> >=20
> > Currently we are using closed Nokia proprietary CAL library.
> >=20
> > Steps 1) and 2) needs closed library, step 4) needs dbus call.
>=20
> I guess pointer to the source code implementing this would be
> welcome.

Here is current code: https://github.com/community-ssu/wl1251-cal

(there is implemented also Maemo netlink interface)

> > > But on other devices that use wl1251, but for instance have no
> > > userspace helper the request to userspace will fail (after 60
> > > sec?) and try VFS after that. Maybe not so nice.
> >=20
> > Currently support for those devices is broken (like for N900) as
> > without proper NVS data they do not work correctly...
>=20
> Is it expected to work at all, perhaps with degraded performance /
> range? Because it seems to work for me.

Yes, some degraded performance or problems with connecting is expected.=20
And random MAC address at every boot. Plus some regulatory problems in=20
=46CC countries.

=2D-=20
Pali Roh=C3=A1r
pali.rohar@gmail.com

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