linux-kernel - Re: [PATCH v7 2/5] dt-bindings: clock: renesas,r9a06g032-sysctrl: documentation

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Date:   Thu, 31 May 2018 11:16:53 +0100
From:   M P <buserror@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     michel.pollet@...renesas.com, linux-renesas-soc@...r.kernel.org,
        Simon Horman <horms@...ge.net.au>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        buserror+upstream@...il.com,
        Michael Turquette <mturquette@...libre.com>, sboyd@...nel.org,
        robh+dt@...nel.org, mark.rutland@....com, geert+renesas@...der.be,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/5] dt-bindings: clock: renesas,r9a06g032-sysctrl: documentation

Hi Geert,

On Fri, 25 May 2018 at 10:23, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Michel,
>
> On Thu, May 24, 2018 at 11:28 AM, Michel Pollet
> <michel.pollet@...renesas.com> wrote:
> > The Renesas R9A06G032 SYSCTRL node description.
> >
> > Signed-off-by: Michel Pollet <michel.pollet@...renesas.com>
>
> Thanks for your patch!
>
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/renesas,r9a06g032-sysctrl.txt
> > @@ -0,0 +1,32 @@
> > +* Renesas R9A06G032 SYSCTRL
> > +
> > +Required Properties:
> > +
> > +  - compatible: Must be:
> > +    - "renesas,r9a06g032-sysctrl"
> > +  - reg: Base address and length of the SYSCTRL IO block.
> > +  - #clock-cells: Must be 1
>
> No clocks/clock-names for the external clock inputs?
>
> "RZ/N1 has 3 clock sources, 1 reference clock inputs for RGMII, and 2
>  reference clock outputs for RMII/MII."
>
> Given the documentation explicitly mentions the module clocks are to be
> used for power-management, you may want to add #power-domain-cells as well,
> and let the driver register clock domain. But that can be added later
> (although it will break backwards compatibility with old DTBs).
>
> As PWRCTRL_* registers allow to reset individual modules, #reset-cells is
> another thing to add later.  It's good to start thinking early about how to
> reference resets, though.
> E.g. on other Renesas-SoCs, module resets uses the same numerical
> references as module clocks.

As you said, could we add all that later, as appropriate? Here I tried
to trim it
down to the the bare minimum -- my previous version of the driver had
separate reset  descriptors, but this one has been all compacted to do just
what it's supposed to do: clocks.

Or, so you want to add another DT index to refer to other reset indexes etc?
ie not use the of_clk_src_onecell_get provider? That COULD work and yes, the
indexes would stay the same, I'd just have to get the reset descriptor from the
clock object. We haven't had a use for individual resets so far.

> Gr{oetje,eeting}s,
>
>                         Geert

Cheers,
Michel