Re: [PATCH 4.12 1/2] brcmfmac: don't use 43602a1 firmware for 43602a0 chipset

On 2017-02-24 14:21, Arend Van Spriel wrote:

On 24-2-2017 13:27, Rafał Miłecki wrote:

quoted

From: Rafał Miłecki <rafal@milecki.pl>

43602a0 uses chip revision 0 compared to 43602a1 with revision 1. In
brcmfmac there is support for 43602a1 and from what I know supporting
43602a0 would require loading a different firmware.

This is not necessarily true. It depends on whether the rom image is
different or not and there is no way to tell up front. So if a0 has 
same
rom image as a1 the firmware is compatible and no distinction is 
needed.
This tends to be the case for chips that only change the digit and not
the letter in the chip revision. Anyway, I do not know if a0 has
different rom image, but the a0 was never sold so there is no harm in
keeping it as is.

Just to be sure (I don't have such a good hardware knowledge):
1) Does ROM image mean some code that is permanently on the device?
2) Does firmware mean code we upload from the host driver?

I'm not sure if I understand the rest of your description.

AFAIU first you said ROM image tends to be the same on chipset 
variations using
the same letter. If this is so, why we need different firmware for 
43602a0 and
43602a1? Or different firmware for 43570a0 and 43570a2?

Also if what you said about sharing one ROM image between chip 
variations using
the same letter was correct, shouldn't you expect the same ROM image on 
43602a0
and 43602a1?

Forgive me if something of this is obvious for you, I just don't have 
access to
any Broadcom internal documentation :)