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

From: Andre Przywara <andre.przywara@arm.com>
To: Wilken Gottwalt <wilken.gottwalt@posteo.net>
Cc: Bastian Germann <bage@debian.org>,
	Ohad Ben-Cohen <ohad@wizery.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Chen-Yu Tsai <wens@csie.org>,
	Samuel Holland <samuel@sholland.org>,
	linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, devicetree@vger.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: hwlock: sun6i: Add missing names
Date: Tue, 14 Feb 2023 12:12:17 +0000	[thread overview]
Message-ID: <20230214121217.43f6124f@donnerap.cambridge.arm.com> (raw)
In-Reply-To: <20230214104554.35338faa@posteo.net>

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

Hi,

> On Tue, 14 Feb 2023 00:19:29 +0100
> Bastian Germann <bage@debian.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