Re: wl1251 & mac address & calibration data

From: Pali RohÃr
Date: Mon Nov 21 2016 - 10:52:19 EST


On Friday 11 November 2016 18:20:50 Pali RohÃr wrote:
> Hi! I will open discussion about mac address and calibration data for
> wl1251 wireless chip again...
>
> Problem: Mac address & calibration data for wl1251 chip on Nokia N900
> are stored on second nand partition (mtd1) in special proprietary format
> which is used only for Nokia N900 (probably on N8x0 and N9 too).
> Wireless driver wl1251.ko cannot work without mac address and
> calibration data.
>
> Absence of mac address cause that driver generates random mac address at
> every kernel boot which has couple of problems (unstable identifier of
> wireless device due to udev permanent storage rules; unpredictable
> behaviour for dhcp mac address assignment, mac address filtering, ...).
>
> Currently there is no way to set (permanent) mac address for network
> interface from userspace. And it does not make sense to implement in
> linux kernel large parser for proprietary format of second nand
> partition where is mac address stored only for one device -- Nokia N900.
>
> Driver wl1251.ko loads calibration data via request_firmware() for file
> wl1251-nvs.bin. There are some "example" calibration file in linux-
> firmware repository, but it is not suitable for normal usage as real
> calibration data are per-device specific.
>
> So questions are:
>
> 1) How to set mac address from userspace for that wl1251 interface? In
> userspace I can write parser for that proprietary format of nand
> partition and extract mac address from it

Proposed solutions for 1)

* Introduce new IOCL for setting that permanent mac address from
userspace. Currently we have IOCL for get request

* Use request_firmware() (with flag from 2)) to ask for mac address from
userspace. This is already used by wl12xx driver (as mac address is
part of calibration data firmware file)

* Allow to set mac address via sysfs file, e.g.
/sys/class/ieee80211/phy0/macaddress

> 2) How to send calibration data to wl1251 driver? Those are again stored
> in proprietary format and I can write userspace parser for it.

Proposed solution for 2)

Introduce new flag for request_firmware(), so it first try to use
userspace helper for loading firmware file with possibility to fallback
to direct VFS access.


So... what do you think about it?

--
Pali RohÃr
pali.rohar@xxxxxxxxx