Re: [Patch 1/3] ARM: dts: am43xx: add support for clkout1 clock

[Tero Kristo]

On 30/10/2019 21:59, Benoit Parrot wrote:
> Tony Lindgren <tony@xxxxxxxxxxx> wrote on Wed [2019-Oct-23 08:56:57 -0700]:
> > * Tony Lindgren <tony@xxxxxxxxxxx> [191022 16:56]:
> > > * Tero Kristo <t-kristo@xxxxxx> [191022 16:48]:
> > > > On 22/10/2019 19:21, Benoit Parrot wrote:
> > > > > Tony Lindgren <tony@xxxxxxxxxxx> wrote on Tue [2019-Oct-22 08:48:16 -0700]:
> > > > > > * Benoit Parrot <bparrot@xxxxxx> [191016 18:47]:
> > > > > > > --- a/arch/arm/boot/dts/am43xx-clocks.dtsi
> > > > > > > +++ b/arch/arm/boot/dts/am43xx-clocks.dtsi
> > > > > > > @@ -704,6 +704,60 @@
> > > > > > >    		ti,bit-shift = <8>;
> > > > > > >    		reg = <0x2a48>;
> > > > > > >    	};
> > > > > > > +
> > > > > > > +	clkout1_osc_div_ck: clkout1_osc_div_ck {
> > > > > > > +		#clock-cells = <0>;
> > > > > > > +		compatible = "ti,divider-clock";
> > > > > > > +		clocks = <&sys_clkin_ck>;
> > > > > > > +		ti,bit-shift = <20>;
> > > > > > > +		ti,max-div = <4>;
> > > > > > > +		reg = <0x4100>;
> > > > > > > +	};
> > > > > >
> > > > > > Here too please describe why the clock names are not generic.
> > > > >
> > > > > Tero originally had this patch in the kernel so this is somewhat of a
> > > > > revert. Since these "clock" were removed. If the name syntax is no longer
> > > > > valid for some reason, then I will need a little more informations to
> > > > > proceed.
> > > > >
> > > > > Tero, can you assist here?
> > > >
> > > > This one is just following the naming convention of the rest of the clocks
> > > > atm.
> > > >
> > > > If we need to fix all the underscore name clocks, that requires pretty much
> > > > complete revamp of both the dts data + clock data under the clock driver,
> > > > and it is not backwards compatible either. How should we tackle that one?
> > > >
> > > > We could maybe add support code in kernel to do s/-/_/g for the "new" clocks
> > > > so that their parent-child relationships would be retained, and then convert
> > > > the clocks in phases.
> > >
> > > Well some of them can be fixed by configuring things based
> > > on the compatible value and then the node name can be just
> > > clock like it should be.
> > >
> > > Here too one option would be to add custom compatibles like:
> > >
> > > compatible = "ti,clkout1-osc-div", "ti,divider-clock";
> > >
> > > And then have match data configure the rest.
> > >
> > > The other option would be to have lookup tables in the clock
> > > driver based on the SoC and reg address.
> > >
> > > This is a hidden mine though.. We've hit it already several times,
> > > and any dts clean-up effort has a chance of breaking things.
> >
> > Hmm maybe in this case just doing this is enough:
> >
> > clkout1_osc_div_ck: clock@4100 {
> > 	...
> > }
>
> But then we would end up with 6 clock node with the same name "clock@4100",
> doesn't pose a problem somewhere?

Yeah, clk core would not know which one to use then.

> Tero?
>
> Benoit
>
> > Or do all the TI clocks we have have a dependency to the
> > node naming?

This is a feature of clock core. Clock parents need to have distinct 
names, otherwise it won't work.

-Tero
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