[linux-sunxi] Re: [PATCH 1/4] brcmfmac: Add brcm,nvram_file_name dt property

[Priit Laes]

On Wed, 2016-06-29 at 21:33 +0200, Arnd Bergmann wrote:
> On Wednesday, June 29, 2016 8:51:44 PM CEST Arend Van Spriel wrote:
> > > Typical wifi devices will have some sort of non volatile storage
> > > on board to not only store the ethernet(mac) address, but also
> > > to contain e.g. info about the antenna gain so that the firmware
> > > and/or the driver can take the antenna gain into account and
> > > ensure
> > > that they never exceed the maximum allowed broadcast strength.
> > > 
> > > However on some embedded devices there is no non-volatile storage
> > > for the wifi (for cost reasons) and instead this configuration
> > > info
> > > (which is board / pcb specific) is loaded in the form of a
> > > file which contains the contents which would normally be in the
> > > non-volatile storage.
> > > 
> > > Since we are dealing with a per-board config-file here, which is
> > > loaded from the os filesystem we really need to specify a
> > > basename
> > > here as the list of possible boards is endless, so we cannot
> > > have a lookup table in the driver.
> > 
> > As Jonas mentioned the general principle of device tree is to be
> > agnostic with regards to OS and/or driver as you undoubtedly know.
> > His
> > proposal seems like a usable solution for your problem while
> > complying
> > to the device tree principle. So instead of overriding the default
> > brcmfmac should modify it when dt specifies the "module" property,
> > ie:
> > 
> > no "module" in DT:      nvram filename = brcm/brcmfmac43362-
> > sdio.txt
> > "module=ap6210" in DT:  nvram filename = brcm/brcmfmac43362-
> > ap6210.txt
> > 
> > By the way, the example in the bindings file does not seem to
> > specify a
> > basename, but path+basename+fileext.
> 
> What is the size of this nvram file? As it's board specific, I wonder
> if we can simply include it inside of the DT verbatim. I remember
> doing that (in the pre-dtb days, on real open firmware) for the
> "spidernet"
> ethernet driver.

It contains a bit too much info:

This is what CubieTruck requires:

http://dl.cubieboard.org/public/Cubieboard/benn/firmware/ap6210/nvram_a
p6210.txt