Re: [PATCH v7 5/7] arm64: dts: ti: k3-j784s4-mcu: Add the mcu domain watchdog instances

[J, KEERTHY]

On 10/6/2023 5:31 PM, Nishanth Menon wrote:
> On 17:22-20231006, J, KEERTHY wrote:
> > On 10/6/2023 5:04 PM, Nishanth Menon wrote:
> > > On 09:58-20231006, Keerthy wrote:
> > > > There are totally 2 instances of watchdog module in MCU domain.
> > > > These instances are coupled with the MCU domain R5F instances.
> > >
> > > > Disabling them as they are not used by Linux.
> > > Device tree is hardware description - not tied to how Linux uses it.
> > >
> > > Reason these wdts are disabled by default is because they are tightly
> > > coupled with R5Fs.
> > >
> > > > Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> > > > ---
> > > >    .../boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi     | 24 +++++++++++++++++++
> > > >    1 file changed, 24 insertions(+)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi b/arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi
> > > > index a7b5c4cb7d3e..809a0b1cf038 100644
> > > > --- a/arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi
> > > > +++ b/arch/arm64/boot/dts/ti/k3-j784s4-mcu-wakeup.dtsi
> > > > @@ -714,4 +714,28 @@
> > > >    		ti,esm-pins = <63>;
> > > >    		bootph-pre-ram;
> > > >    	};
> > > > +
> >
> > Nishanth,
> >
> > Below i have addressed the coupling with R5Fs & MCU domains watcdogs.
> >
> > > > +	/*
> > > > +	 * The 2 RTI instances are couple with MCU R5Fs so keeping them
> > > > +	 * disabled as these will be used by their respective firmware
>
> This description is best in the commit message
>
> > > > +	 */
> > > > +	mcu_watchdog0: watchdog@40600000 {
> > > > +		compatible = "ti,j7-rti-wdt";
> > > > +		reg = <0x00 0x40600000 0x00 0x100>;
> > > > +		clocks = <&k3_clks 367 1>;
> > > > +		power-domains = <&k3_pds 367 TI_SCI_PD_EXCLUSIVE>;
> > > > +		assigned-clocks = <&k3_clks 367 0>;
> > > > +		assigned-clock-parents = <&k3_clks 367 4>;
> > > > +		status = "disabled";
> > > > +	};
> > > > +
> > > > +	mcu_watchdog1: watchdog@40610000 {
> > > > +		compatible = "ti,j7-rti-wdt";
> > > > +		reg = <0x00 0x40610000 0x00 0x100>;
> > > > +		clocks = <&k3_clks 368 1>;
> > > > +		power-domains = <&k3_pds 368 TI_SCI_PD_EXCLUSIVE>;
> > > > +		assigned-clocks = <&k3_clks 368 0>;
> > > > +		assigned-clock-parents = <&k3_clks 368 4>;
> > >
> > > Please DONOT ignore the review comments - I did ask the documentation in
> > > dts as well. reason being that this is what people will see rather than
> > > dig up the commit log. it should be intutive when reading the dts why
> > > nodes are disabled by default Vs the standard of leaving it enabled by
> > > default. Given esp that these peripherals do not have anything to do
> > > with board semantics (pinmux or something similar) to be complete.
> >
> > As mentioned above. I added single comment for addressing both the
> > watchdogs.
>
> I missed it completely. Now that I think of it, I seem to have missed
> having seen it in previous rev reviews as well, and there is a reason
> for it: See [1] clarifying comment - nodes reserved for firmware usage
> have convention of "reserved" as status and documentation immediately
> above the status to help clarify the reason in-context. That is more
> readable than having to scroll up to find the rationale.
>
> [1] https://lore.kernel.org/all/20231006114422.avymeap7h5ocs6zq@dreadlock/

Thanks Nishanth. I agree reserved is better and I will add a comment 
something like below:

/* Tightly coupled to R5F */
status = "reserved";

- Keerthy
>