linux-kernel - Re: [PATCH 2/3] dt-bindings: hwlock: sun6i: Add missing names

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Date:   Tue, 14 Feb 2023 12:12:17 +0000
From:   Andre Przywara <andre.przywara@....com>
To:     Wilken Gottwalt <wilken.gottwalt@...teo.net>
Cc:     Bastian Germann <bage@...ian.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Samuel Holland <samuel@...lland.org>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: hwlock: sun6i: Add missing names

On Tue, 14 Feb 2023 09:45:54 +0000
Wilken Gottwalt <wilken.gottwalt@...teo.net> wrote:

Hi,

> On Tue, 14 Feb 2023 00:19:29 +0100
> Bastian Germann <bage@...ian.org> wrote:
> 
> > The allwinner,sun6i-a31-hwspinlock.yaml binding needs clock-names
> > and reset-names set to "ahb" as required by the driver.  
> 
> Hmm, this one is a bit odd. If you look into my earlier versions of the
> patchset, you may notice, that I actually included these bindings and they
> were refused. I think the argumentation was like
> "there is only one bus = no need for it".

That's interesting, because your driver implementation relies on there
being a clock name. And if I chased down devm_clk_get() correctly, there
must be a named clock in the DT, otherwise it would fail? I haven't tested
this, though, but I guess this is the  reason for Bastian's patch.

Regarding "one bus clock only": while this is true, I think there
is (or was?) also the rationale of using names being more future-proof, so
adding clocks (for future hardware revisions) can be done more easily,
without breaking compatibility. It's not a big problem, since you probably
have a new compatible string in this case anyway, but it also doesn't
hurt, and allows to use more generic helpers like devm_clk_get().

> If it gets accepted now, I really like to know why. (It was some trouble
> back then to get the documentation properly done and accepted.)

IIUC, it simply doesn't work without a clock-names property.

Cheers,
Andre