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

From: Frank Li
Date: Fri May 17 2024 - 13:10:30 EST


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