RE: [PATCH v2 1/3] dt-bindings: arm: renesas: Document Renesas RZ/V2M System Configuration

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Hi Geert,

Thanks for the feedback.

> Subject: Re: [PATCH v2 1/3] dt-bindings: arm: renesas: Document Renesas
> RZ/V2M System Configuration
> 
> Hi Biju,
> 
> On Mon, Nov 14, 2022 at 6:05 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> > > From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> On
> > > 14/11/2022 17:44, Biju Das wrote:
> > > >>>>> If the hardware manual said this is called "foo-whatever-name"
> > > >>>>> or "rz85736dfnx2", you would use it as well?
> > > >>>>>
> > > >>>>> Node names should be generic.
> > > >>>
> > > >>> I got the following feedback from LSI team.
> > > >>>
> > > >>> *The reason why we use "configuration" and not "controller" is
> > > >>> the possibility that users might take it to mean "control" of
> > > >>> system operation (product operation). This unit determines how
> > > >>> the whole LSI
> > > >> configure to operate LSI, so we use "configuration" for this IP name.
> > > >>>
> > > >>> As per this it is not a controller. It is a Configuration IP.
> > > >>>
> > > >>> What should be generic node name for system configuration IP?
> > > >>
> > > >> Then it's closer to chipid and should be in hwinfo?
> > > >
> > > > You mean, sys: hwinfo@a3f03000 instead of sys: system-
> > > configuration@a3f03000 ??
> > >
> > > Rather be put in hwinfo directory. Typical name is "chipid", but I
> > > don't know if your device is a chipid.
> >
> > This IP is for sure not a chipid. We can detect SoC version. That is
> > one of the functions provided by this IP.
> >
> > > > Also the same IP block is present on rz/v2ma as well?
> > > >
> > > > Shall I use the same file renesas,rzv2m-sys.yaml for both
> > > > r9a09g011-sys and
> > > r9a09g055-sys?
> 
> Are they sufficiently similar? E.g. we have renesas,rst.yaml for the various
> R-Car reset controllers, which have different register layouts.

I have been told both RZ/V2M and RZ/V2MA are exactly same, but later does not have ISP module.

> 
> If the SoC version register is located at the same offset, it might be
> worthwhile to add a family-specific compatible value, too, so the soc_device
> driver doesn't have to contain a big list to match against.

The SoC version registers are located at the same offset.
But there is no way to distinguish both the SoCs.

> 
> > > >> Anyway, you wrote in bindings description: "performs system
> > > >> control", so what can I say?
> > > >
> > > > SYS functional description is as follows.
> > > >
> > > > The SYS controls the overall configuration of the chip, such as
> > >
> > > Exactly, it controls, so it is a controller... Anyway, do not
> > > introduce your own names, but use something generic. There is no
> > > single reference of "system-configuration".
> >
> > The main functionality of the chip is Bank address configuration,
> >
> > Bank Address Switching
> >
> > The SYS has a bank switching register to extend the two higher-order
> > bits of the addresses of the following IP modules which have only
> > 32-bit (4-GB) address spaces. It makes 4 or more Gbytes of the address
> space accessible by switching the bank address.
> >
> > Target unit 1: DRP-AI, eMMC, SDI0/1, ETHER, PCIe, USB, GRP, VCD Target
> > unit 2: DMAC
> >
> > The other control functionalities mentioned in the IP are simple one.
> >
> > As you said, It is unique IP. Probably in future some other SoC
> > manufactures may come with similar IP for system configuration like Bank
> switching. With Bank switching we can switch from 32 bit ->34 bit addresses.
> 
> Sounds like a system-controller to me ;-) So that looks like the most
> appropriate generic name.

OK, will use node name as 'system-controller@a3f03000' and
Label name as "sys" to match with HW manual.

Cheers,
Biju




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