linux-kernel - Re: [PATCH] wifi: brcmfmac: of: Support interrupts-extended

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Date: Sat, 22 Jun 2024 16:07:37 +0200
From: Alex Bee <knaerzche@...il.com>
To: Arend Van Spriel <arend.vanspriel@...adcom.com>,
 Kalle Valo <kvalo@...nel.org>, linux-wireless@...r.kernel.org,
 brcm80211@...ts.linux.dev, brcm80211-dev-list.pdl@...adcom.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] wifi: brcmfmac: of: Support interrupts-extended


Am 22.06.24 um 15:49 schrieb Arend Van Spriel:
> On June 22, 2024 3:38:32 PM Arend Van Spriel 
> <arend.vanspriel@...adcom.com> wrote:
>
>> On June 22, 2024 12:56:02 AM Alex Bee <knaerzche@...il.com> wrote:
>>
>>> This "new" version of defining external interrupts is around for a very
>>> long time now and supported and preferred by irq_of_parse_and_map
>>> respectively of_irq_parse_one.
>>>
>>> Support it in brcmfmac as well by checking if either "interrupts" or
>>> "interrupts-extended" property exists as indication if 
>>> irq_of_parse_and_map
>>> should be called.
>>
>> All very interesting, but why should we add code for something that 
>> is not
>> specified in the bindings documentation?
>>
>> NAK (for now). Feel free to update the bindings document.
>
Sure, if you insist on it, I can update the bindings document. So far not
many (no) users did that, as it is clearly specified as an alternative in
devicetree/bindings/interrupt-controller/interrupts.txt (sure, it's not yet
converted to yaml yet).
> So looked up the interrupts-extended definition:
>
> The "interrupts-extended" property is a special form; useful when a 
> node needs
> to reference multiple interrupt parents or a different interrupt 
> parent than
> the inherited one. Each entry in this property contains both the 
> parent phandle
> and the interrupt specifier.
>
They point in this particular case is not how many interrupts exsist, but
"... or a different interrupt parent than
the inherited ..." which is almost always the case for brcmfmac, as it
usually specifies a gpio controller as interrupt parent. So:

...
         interrupt-parent = <&gpio0>;
         interrupts = <RK_PA0 IRQ_TYPE_LEVEL_HIGH>;
...

gets to (a single line):
...
     interrupts-extended:  = <&gpio0 RK_PA0 IRQ_TYPE_LEVEL_HIGH>;
...

Which is a much nicer form, imho.
And by the way for instance
arch/arm/boot/dts/qcom/qcom-apq8026-lg-lenok.dts already uses it that way
and the interrupt will currently not picked up (at least not by this
driver).

Alex

> Given that brcmfmac device will only have one interrupt item defined 
> there is no need to use it. If someone can give a good argument to 
> support it please chime in.
>
> Regards,
> Arend
>
>
>