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

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Message-ID: <CACRpkdbpJ8fw0UsuHXGX43JRyPy6j8P41_5gesXOmitHvyoRwQ@mail.gmail.com>
Date:   Sat, 26 Nov 2022 22:45:33 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Kalle Valo <kvalo@...nel.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Alvin Šipraga <ALSI@...g-olufsen.dk>,
        Hector Martin <marcan@...can.st>,
        "~postmarketos/upstreaming@...ts.sr.ht" 
        <~postmarketos/upstreaming@...ts.sr.ht>,
        "martin.botka@...ainline.org" <martin.botka@...ainline.org>,
        "angelogioacchino.delregno@...ainline.org" 
        <angelogioacchino.delregno@...ainline.org>,
        "marijn.suijten@...ainline.org" <marijn.suijten@...ainline.org>,
        "jamipkettunen@...ainline.org" <jamipkettunen@...ainline.org>,
        Arend van Spriel <aspriel@...il.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Marek Vasut <marex@...x.de>,
        "Zhao, Jiaqing" <jiaqing.zhao@...el.com>,
        "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
        Soon Tak Lee <soontak.lee@...ress.com>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "brcm80211-dev-list.pdl@...adcom.com" 
        <brcm80211-dev-list.pdl@...adcom.com>,
        "SHA-cyfmac-dev-list@...ineon.com" <SHA-cyfmac-dev-list@...ineon.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] brcmfmac: Add support for BCM43596 PCIe Wi-Fi

On Fri, Nov 25, 2022 at 1:25 PM Kalle Valo <kvalo@...nel.org> wrote:
> Konrad Dybcio <konrad.dybcio@...aro.org> writes:
>
> > On 25.11.2022 12:53, Kalle Valo wrote:
> >> Konrad Dybcio <konrad.dybcio@...aro.org> writes:
> >>
> >>> On 21.11.2022 14:56, Linus Walleij wrote:
> >>>> On Fri, Nov 18, 2022 at 5:47 PM Konrad Dybcio <konrad.dybcio@...aro.org> 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