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

On Wednesday, June 29, 2016 8:51:44 PM CEST Arend Van Spriel wrote:

quoted

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.

	Arnd