Re: [PATCH v2] brcmfmac: Add support for BCM43596 PCIe Wi-Fi

[Linus Walleij]

On Fri, Nov 25, 2022 at 1:25 PM Kalle Valo <kvalo@xxxxxxxxxx> wrote:
> Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> writes:
>
> > On 25.11.2022 12:53, Kalle Valo wrote:
> >> Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> writes:
> >>
> >>> On 21.11.2022 14:56, Linus Walleij wrote:
> >>>> On Fri, Nov 18, 2022 at 5:47 PM Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
> >>>>
> >>>>> I can think of a couple of hacky ways to force use of 43596 fw, but I
> >>>>> don't think any would be really upstreamable..
> >>>>
> >>>> If it is only known to affect the Sony Xperias mentioned then
> >>>> a thing such as:
> >>>>
> >>>> if (of_machine_is_compatible("sony,xyz") ||
> >>>>     of_machine_is_compatible("sony,zzz")... ) {
> >>>>    // Enforce FW version
> >>>> }
> >>>>
> >>>> would be completely acceptable in my book. It hammers the
> >>>> problem from the top instead of trying to figure out itsy witsy
> >>>> details about firmware revisions.
> >>>>
> >>>> Yours,
> >>>> Linus Walleij
> >>>
> >>> Actually, I think I came up with a better approach by pulling a page
> >>> out of Asahi folks' book - please take a look and tell me what you
> >>> think about this:
> >>>
> >>> [1]
> >>> https://github.com/SoMainline/linux/commit/4b6fccc995cd79109b0dae4e4ab2e48db97695e7
> >>> [2]
> >>> https://github.com/SoMainline/linux/commit/e3ea1dc739634f734104f37fdbed046873921af7

Something in this direction works too.

The upside is that it tells all operating systems how to deal
with the firmware for this hardware.

> >> Instead of a directory path ("brcm/brcmfmac43596-pcie") why not provide
> >> just the chipset name ("brcmfmac43596-pcie")? IMHO it's unnecessary to
> >> have directory names in Device Tree.
> >
> > I think it's common practice to include a full $FIRMWARE_DIR-relative
> > path when specifying firmware in DT, though here I left out the board
> > name bit as that's assigned dynamically anyway. That said, if you don't
> > like it, I can change it.
>
> It's just that I have understood that Device Tree is supposed to
> describe hardware and to me a firmware directory "brcm/" is a software
> property, not a hardware property. But this is really for the Device
> Tree maintainers to decide, they know this best :)

I would personally just minimize the amount of information
put into the device tree to be exactly what is needed to find
the right firmware.

brcm,firmware-compatible = "43596";

since the code already knows how to conjure the rest of the string.

But check with Rob/Krzysztof.

Yours,
Linus Walleij