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Date: Fri, 17 May 2024 18:13:21 +0100
From: Conor Dooley <conor@kernel.org>
To: Frank Li <Frank.li@nxp.com>
Cc: Shengjiu Wang <shengjiu.wang@gmail.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Shengjiu Wang <shengjiu.wang@nxp.com>, abelvesa@kernel.org,
	peng.fan@nxp.com, mturquette@baylibre.com, robh@kernel.org,
	krzk+dt@kernel.org, conor+dt@kernel.org, shawnguo@kernel.org,
	s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
	marex@denx.de, linux-clk@vger.kernel.org, imx@lists.linux.dev,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, p.zabel@pengutronix.de
Subject: Re: [PATCH v3 3/6] dt-bindings: clock: imx8mp: Add reset-controller
 sub-node
Message-ID: <20240517-afterglow-sandstone-076e593fedf8@spud>
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On Fri, May 17, 2024 at 01:10:05PM -0400, Frank Li wrote:
> On Fri, May 17, 2024 at 05:21:32PM +0100, Conor Dooley wrote:
> > On Thu, May 16, 2024 at 11:56:27PM -0400, Frank Li wrote:
> >=20
> > > Look like it is easy to register auxdev "reset" devices. But I have a
> > > problem. How to use it by DT phandle?  "reset" devices is service pro=
vider.
> > > Some client will use it.
> > >=20
> > > Generally, reset node will used by other devices nodes. like
> > >=20
> > > ABC: reset {
> > > 	compatible=3D"simple-reset";
> > > 	...
> > > }
> > >=20
> > > other node will use "reset =3D <&ABC 0>".  If use auxdev, how to get =
&ABC
> > > in dts file.
> >=20
> > Whether or not you use auxdev or any other method etc, does not matter
> > in a DT system, the consumer will always have a phandle to the provider
> > node:
> >=20
> > ABC: whatever {
> > 	compatible =3D "whatever";
> > 	#clock-cells =3D <...>;
> > 	#reset-cells =3D <...>;
> > }
> >=20
> > something-else {
> > 	clocks =3D <&ABC ...>;
> > 	resets =3D <&ABC ...>;
> > }
>=20
>=20
> It goes back to old problem, "reset-cells" will be in "clock-controller".
>=20
> clock-controller@30e20000 {
>         compatible =3D "fsl,imx8mp-audio-blk-ctrl", "syscon", "simple-mfd=
";
>         reg =3D <0x30e20000 0x10000>;
> 	...
> =09
> 	#reset-cells =3D <...>;
> 	^^^
>     };
>=20
> If create new "whatever" auxdev bus driver which included two aux devices=
,=20
> (clock and reset).=20
>=20
> it will be similar with mfd. Still need change
> clock-controller@30e20000 drivers.
>=20
> "Which is I suspect is gonna require a change to your clock driver,
> because the range in the existing clock nodes:
> 	audio_blk_ctrl: clock-controller@30e20000 {
> 		compatible =3D "fsl,imx8mp-audio-blk-ctrl";
> 		reg =3D <0x30e20000 0x10000>;
> 	};
> would then have to move to the mfd parent node, and your clock child
> would have a reg property that overlaps the reset region. You'd need to
> then define a new binding that splits the range in two - obviously
> doable, but significantly more work and more disruptive than using an
> auxdev."
>=20
> So I don't know why auxdev will be better than mfd.

I think Stephen and I have spent enough time trying to explain why using
auxdev is beneficial here. I, at least, won't be wasting any more of my
(metaphorical) breath.

> A possible benefit may be that Auxdev needn't binding doc for clock and
> reset node devices.


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