Re: [PATCH v6 2/2] arm64: dts: sdm845: Add gpu and gmu device nodes

From: Stephen Boyd <sboyd@kernel.org>
To: Doug Anderson <dianders@chromium.org>, Rob Herring <robh@kernel.org>
Cc: Nishanth Menon <nm@ti.com>,
	devicetree@vger.kernel.org,
	Rajendra Nayak <rnayak@codeaurora.org>,
	"open list:THERMAL" <linux-pm@vger.kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Jordan Crouse <jcrouse@codeaurora.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	freedreno <freedreno@lists.freedesktop.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>,
	Viresh Kumar <vireshk@kernel.org>
Subject: Re: [PATCH v6 2/2] arm64: dts: sdm845: Add gpu and gmu device nodes
Date: Thu, 20 Dec 2018 13:29:24 -0800	[thread overview]
Message-ID: <154534136449.79149.14097954220921296509@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <CAL_Jsq+U8Vj4+w6jA+B3_CyG8N==ABbw31nm+LE=6pwXEopApw@mail.gmail.com>

Quoting Rob Herring (2018-12-19 15:47:25)
> On Wed, Dec 19, 2018 at 4:40 PM Doug Anderson <dianders@chromium.org> wrote:
> > On Wed, Dec 19, 2018 at 12:40 PM Doug Anderson <dianders@chromium.org> wrote:
> > > On Wed, Dec 19, 2018 at 12:09 PM Rob Herring <robh@kernel.org> wrote:
> > > ...but it does have a frequency, doesn't it?
> > >
> > > +   compatible = "operating-points-v2-qcom-level";
> > > +
> > > +   opp-710000000 {
> > > +     opp-hz = /bits/ 64 <710000000>;
> > > +     qcom,level = <RPMH_REGULATOR_LEVEL_TURBO_L1>;
> > > +   };
> >
> > Ah, I perhaps see the confusion.  So Rajendra's usage of
> > "operating-points-v2-qcom-level" [1] doesn't have a frequency but
> > Jordan's do.  So I guess it makes sense that Jordan's have the
> > fallback compatible but Rajendra's don't?
> 
> Is having it useful to s/w that doesn't understand
> "operating-points-v2-qcom-level"? If so, then add
> "operating-points-v2". If not, then don't.

The only benefit I see in having "operating-points-v2" is that we don't
need to update the of_skipped_node_table[] in drivers/platform/of.c to
have all the variants of operating-points-v2-* when they decide to not
use anything from the "base" binding.

If that fails to work because opp-hz is required for the
"operating-points-v2" binding but sometimes
operating-points-v2-qcom-level doesn't require it I guess we need to
update the skip table or make some generic property like
'this-is-not-a-device' that these various data tables in DT can be
marked with so we don't make platform devices for them.

Regardless of the above, we should update the binding for
operating-points-v2-qcom-level to say that opp-hz isn't always required
when the qcom-level compatible is present. It looks like it just says
that it builds on top of the opp binding so that's not obvious.

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