Re: [PATCH v1 22/22] riscv: dts: starfive: jhb100: Add clocks and resets nodes

[Changhuang Liang]

Hi, Conor

> On Thu, Apr 02, 2026 at 03:55:23AM -0700, Changhuang Liang wrote:
> > Add clocks and resets nodes for JHB100 RISC-V BMC SoC. They contain
> > sys0crg/sys1crg/sys2crg/per0crg/per1crg/per2crg/per3crg.
> >
> > Signed-off-by: Changhuang Liang <changhuang.liang@xxxxxxxxxxxxxxxx>
> > ---
> >  arch/riscv/boot/dts/starfive/jhb100.dtsi | 198
> > ++++++++++++++++++++++-
> >  1 file changed, 195 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/boot/dts/starfive/jhb100.dtsi
> > b/arch/riscv/boot/dts/starfive/jhb100.dtsi
> > index 4d03470f78ab..700d00f800bc 100644
> > --- a/arch/riscv/boot/dts/starfive/jhb100.dtsi
> > +++ b/arch/riscv/boot/dts/starfive/jhb100.dtsi
> > @@ -4,6 +4,8 @@
> >   */
> >
> >  /dts-v1/;
> > +#include <dt-bindings/clock/starfive,jhb100-crg.h>
> > +#include <dt-bindings/reset/starfive,jhb100-crg.h>
> >
> >  / {
> >  	compatible = "starfive,jhb100";
> > @@ -268,12 +270,96 @@ pmu {
> >  			<0x00 0x22 0xFFFFFFFF 0xFFFFFF22 0x00007FF8>;	/* Event
> ID 34 */
> >  	};
> >
> > -	clk_uart: clk-uart {
> > -		compatible = "fixed-clock"; /* Initial clock handler for UART */
> > +	osc: osc {
> > +		compatible = "fixed-clock";
> >  		#clock-cells = <0>;
> >  		clock-frequency = <25000000>;
> >  	};
> 
> Is this really on the SoC?

This is not on the SoC.

> 
> >
> > +	pll0: pll0 {
> > +		compatible = "fixed-clock";
> > +		#clock-cells = <0>;
> > +		clock-frequency = <2400000000>;
> > +	};
> 
> What's providing all of these PLLs? Are they all fixed-frequency on-chip PLLs
> without an off-chip reference? I find that somewhat unlikely.
> 
> Since devicetrees are now being imported into U-Boot, it's important to make
> sure that I'm not merging fixed-clocks that later get replaced by dedicated
> drivers that U-Boot won't have.
> 
> To that end, I won't apply the series this depends on without this patch being
> applied at the same time.

I am preparing a PLL driver series, but PLL0 and PLL1 will still retain fixed frequencies. 
The reference clock for each PLL comes from the osc. Perhaps I can use "fixed-factor-clock" 
to indicate the relationship of the reference clock.

Best Regards,
Changhuang