linux-kernel - Re: [PATCH v1] dt-bindings: opp: Allow multi-worded node names

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Message-ID: <ab97d384-35ae-3cf4-6011-ce47449268bb@gmail.com>
Date:   Sat, 23 Oct 2021 22:01:13 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rob Herring <robh@...nel.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Stephen Boyd <sboyd@...nel.org>,
        Nishanth Menon <nm@...com>, David Heidelberg <david@...t.cz>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v1] dt-bindings: opp: Allow multi-worded node names

23.10.2021 16:46, Dmitry Osipenko пишет:
> 23.10.2021 16:00, Dmitry Osipenko пишет:
>> 22.10.2021 10:45, Viresh Kumar пишет:
>>> On 22-10-21, 10:39, Dmitry Osipenko wrote:
>>>> What we currently have for Tegra is a tegra-opps.dtsi and tegra.dtsi
>>>> which includes the OPP's dtsi.
>>>>
>>>> the tegra-opps.dtsi has this structure:
>>>>
>>>> table: devname-opp-table {
>>>> 	opp: ...
>>>> };
>>>>
>>>> and tegra.dtsi:
>>>>
>>>> #include "tegra-opps.dtsi"
>>>>
>>>> device@...0 {
>>>> 	operating-points-v2 = <&table>;
>>>> };
>>>>
>>>> It just occurred to me that there is no need to move all tables to
>>>> tegra.dtsi, but change structure of tegra-opps.dtsi to:
>>>>
>>>> device@...0 {
>>>> 	operating-points-v2 = <&table>;
>>>>
>>>> 	table: opp-table {
>>>> 		opp: ...
>>>> 	};
>>>> };
>>>
>>> I thought you would have already thought about that and I was surprised when you
>>> saw the tables are big enough to be moved. I was wondering what does it really
>>> mean :)
>>>
>>>> Then there no need to change current naming scheme. Let me try to
>>>> implement it and see how it goes.
>>>
>>> That's good then.
>>>
>>
>> I implemented that approach and it works, but there are two problems:
>>
>> 1. I had to factor out OPP tables from SPI device-tree nodes because DTC doesn't allow to have them within SPI nodes [1] and dtb fails to compile.
>>
>> [1] https://elixir.bootlin.com/linux/v5.15-rc6/source/scripts/dtc/checks.c#L1141
>>
>> 2. dtbs_check now warns about every opp-table sub-node, like this:
>>
>> /home/runner/work/linux/linux/arch/arm/boot/dts/tegra30-asus-nexus7-grouper-E1565.dt.yaml: memory-controller@...0f400: 'opp-table' does not match any of the regexes: '^emc-timings-[0-9]+$', 'pinctrl-[0-9]+'
>> 	From schema: /home/runner/work/linux/linux/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra30-emc.yaml
>>
> 
> Thinking more about this, it's not a good idea to add new sub-node to
> nodes which already have sub-nodes because existing driver code that
> parses sub-nodes may not be ready to face the new opp-table sub-node.
> 
> I'll revert back to the previous variant with distinct opp-table nodes.
> 

I renamed OPP tables in accordance to the current opp-table-name
pattern, but still OPP entry names have multiple words on Tegra and it's
not feasible to change that without hurting readability. I'll prepare v3
that will only update pattern of OPP entries.