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Date:   Mon, 28 Nov 2022 15:40:27 +0100
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Subject: Re: [PATCH v2] brcmfmac: Add support for BCM43596 PCIe Wi-Fi
To:     Linus Walleij <linus.walleij@linaro.org>,
        Kalle Valo <kvalo@kernel.org>
Cc:     =?UTF-8?Q?Alvin_=c5=a0ipraga?= <ALSI@bang-olufsen.dk>,
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        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Rob Herring <robh+dt@kernel.org>
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From:   Konrad Dybcio <konrad.dybcio@linaro.org>
In-Reply-To: <CACRpkdbpJ8fw0UsuHXGX43JRyPy6j8P41_5gesXOmitHvyoRwQ@mail.gmail.com>
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On 26.11.2022 22:45, Linus Walleij wrote:
> On Fri, Nov 25, 2022 at 1:25 PM Kalle Valo <kvalo@kernel.org> wrote:
>> Konrad Dybcio <konrad.dybcio@linaro.org> writes:
>>
>>> On 25.11.2022 12:53, Kalle Valo wrote:
>>>> Konrad Dybcio <konrad.dybcio@linaro.org> writes:
>>>>
>>>>> On 21.11.2022 14:56, Linus Walleij wrote:
>>>>>> On Fri, Nov 18, 2022 at 5:47 PM Konrad Dybcio <konrad.dybcio@linaro.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

Krzysztof, Rob [added to CC] - can I have your opinions?

Konrad