linux-kernel - Re: [PATCH v2 6/6] of: of_cpu_phandle_to

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Message-ID: <20250506143125.00002cae.alireza.sanaee@huawei.com>
Date: Tue, 6 May 2025 14:31:25 +0100
From: Alireza Sanaee <alireza.sanaee@...wei.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: <devicetree@...r.kernel.org>, <robh@...nel.org>,
	<jonathan.cameron@...wei.com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>,
	<mark.rutland@....com>, <shameerali.kolothum.thodi@...wei.com>
Subject: Re: [PATCH v2 6/6] of: of_cpu_phandle_to_id to support SMT threads

On Tue, 6 May 2025 12:56:43 +0200
Krzysztof Kozlowski <krzk@...nel.org> wrote:

> On 06/05/2025 12:23, Alireza Sanaee wrote:
> > On Sun, 4 May 2025 19:52:34 +0200
> > Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >   
> >> On 04/05/2025 19:51, Krzysztof Kozlowski wrote:  
> >>>> In the CPU map, there are two cases that only one occurs at at
> >>>> time. 1) "cpu" = <phandle>
> >>>>     2) "cpus" = <phandle> <index>
> >>>>
> >>>> The first case addresses non-SMTs and the second case addresses
> >>>> SMTs that the variable must be cpu(s) with an index where we
> >>>> later look up the reg array with that.
> >>>>
> >>>>     core0 {
> >>>>       thread0 {
> >>>>         cpus = <&cpu0 0>;    
> >>>
> >>> Not so sure, dtschema says only one item is allowed in the phandle
> >>> and I do not see here binding change.
> >>>
> >>> Although this wasn't even sent to me, so I'll just ignore your
> >>> patchset.    
> >>
> >> Ah, there was no binding in the patchset, so that's why I did not
> >> get it. Makes sense now, but question about missing binding change
> >> stays.
> >>
> >> Best regards,
> >> Krzysztof
> >>  
> > 
> > Hi Krzysztof,
> > 
> > There are some existing bindings in which this pattern has been
> > used, so I don't think I am changing binding really.
> > 
> > https://www.kernel.org/doc/Documentation/devicetree/bindings/thermal/thermal-zones.yaml#:~:text=cooling%2Ddevice%20%3D%20%3C%26CPU0%203%203%3E%2C%20%3C%26CPU1%203%203%3E%2C  
> I do not understand this - it is not cpus phandle. Please respond to
> specific comment: how many arguments are allowed by dtschema for cpus?

Hi Krzysztof,

If you mean checking
here? https://github.com/devicetree-org/dt-schema/blob/e6ea659d2baa30df1ec0fcc4f8354208692489eb/dtschema/schemas/cpu-map.yaml#L110

There is no parameters allowed at this point for cpu phandles in the
cpu-map tree. Of course, this is different than what's been
implemented in the patchset.

> 
> Best regards,
> Krzysztof
>