Re: [PATCH v3 3/6] dt-bindings: clock: imx8mp: Add reset-controller sub-node

From: Frank Li <Frank.li@nxp.com>
To: Conor Dooley <conor@kernel.org>
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
Date: Fri, 17 May 2024 13:10:05 -0400	[thread overview]
Message-ID: <ZkePbZBufOHWQdzM@lizhi-Precision-Tower-5810> (raw)
In-Reply-To: <20240517-gristle-dealt-56b5299b9cb8@spud>

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:
> 
> > 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 provider.
> > Some client will use it.
> > 
> > Generally, reset node will used by other devices nodes. like
> > 
> > ABC: reset {
> > 	compatible="simple-reset";
> > 	...
> > }
> > 
> > other node will use "reset = <&ABC 0>".  If use auxdev, how to get &ABC
> > in dts file.
> 
> 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:
> 
> ABC: whatever {
> 	compatible = "whatever";
> 	#clock-cells = <...>;
> 	#reset-cells = <...>;
> }
> 
> something-else {
> 	clocks = <&ABC ...>;
> 	resets = <&ABC ...>;
> }

It goes back to old problem, "reset-cells" will be in "clock-controller".

clock-controller@30e20000 {
        compatible = "fsl,imx8mp-audio-blk-ctrl", "syscon", "simple-mfd";
        reg = <0x30e20000 0x10000>;
	...

	#reset-cells = <...>;
	^^^
    };

If create new "whatever" auxdev bus driver which included two aux devices, 
(clock and reset). 

it will be similar with mfd. Still need change
clock-controller@30e20000 drivers.

"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 = "fsl,imx8mp-audio-blk-ctrl";
		reg = <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."

So I don't know why auxdev will be better than mfd.

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

Frank

Frank

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