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

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Message-ID: <20250506112520.00004545.alireza.sanaee@huawei.com>
Date: Tue, 6 May 2025 11:25:20 +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 Sun, 4 May 2025 19:51:02 +0200
Krzysztof Kozlowski <krzk@...nel.org> wrote:

> On Fri, May 02, 2025 at 05:13:00PM GMT, Alireza Sanaee wrote:
> > Enhance the API to support SMT threads, this will allow sharing
> > resources among multiple SMT threads.  
> 
> <form letter>
> Please use scripts/get_maintainers.pl to get a list of necessary
> people and lists to CC (and consider --no-git-fallback argument, so
> you will not CC people just because they made one commit years ago).
> It might happen, that command when run on an older kernel, gives you
> outdated entries. Therefore please be sure you base your patches on
> recent Linux kernel.
> 
> Tools like b4 or scripts/get_maintainer.pl provide you proper list of
> people, so fix your workflow. Tools might also fail if you work on
> some ancient tree (don't, instead use mainline) or work on fork of
> kernel (don't, instead use mainline). Just use b4 and everything
> should be fine, although remember about 'b4 prep --auto-to-cc' if you
> added new patches to the patchset.
> </form letter>	
> 
> > 
> > Enabled the sharing of resources, such as L1 Cache and clocks,
> > between SMT threads. It introduces a fix that uses thread IDs to
> > match each CPU thread in the register array within the cpu-node.
> > This ensures that the cpu-map or any driver relying on this API is
> > fine even when SMT threads share resources.
> > 
> > Additionally, I have tested this for CPU based on the discussions
> > in [1], I adopted the new cpu-map layout, where the first parameter
> > is a phandle and the second is the local thread index, as shown
> > below:
> > 
> > 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.
> 
> Best regards,
> Krzysztof
> 

Sorry, I didn't use the script, I will next time.