linux-kernel - Re: [PATCH 2/4] dt-bindings: clock: Add R9A09G057 CPG Clock and Reset Definitions

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Date: Wed, 5 Jun 2024 09:53:31 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Magnus Damm <magnus.damm@...il.com>, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, 
	Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 2/4] dt-bindings: clock: Add R9A09G057 CPG Clock and Reset Definitions

Hi Geert,

On Wed, Jun 5, 2024 at 9:29 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> CC Greg
>
> On Tue, Jun 4, 2024 at 5:46 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Fri, May 24, 2024 at 10:29 AM Prabhakar <prabhakar.csengg@...il.com> wrote:
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > >
> > > Define RZ/V2H(P) (R9A09G057) Clock Pulse Generator module clock outputs
> > > (CPG_CLK_ON* registers), and reset definitions (CPG_RST_* registers)
> > > in Section 4.4.2 and 4.4.3 ("List of Clock/Reset Signals") of the RZ/V2H(P)
> > > Hardware User's Manual (Rev.1.01, Feb. 2024).
> >
> > Hmm, I must have a slightly different Rev. 1.01 ;-)
> >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > > --- /dev/null
> > > +++ b/include/dt-bindings/clock/r9a09g057-cpg.h
>
> > > +/* Clock list */
> >
> > [...]
> >
> > > +#define R9A09G057_USB30_CLK_RESERVED0                  197
> > > +#define R9A09G057_USB30_CLK_RESERVED1                  198
> > > +#define R9A09G057_USB30_CLK_RESERVED2                  199
> > > +#define R9A09G057_USB30_CLK_RESERVED3                  200
>
> [...]
>
> It has been brought to my attention these had been named *RESERVED*
> deliberately, to avoid disclosing their meaning.
> As these definitions are part of the DT ABI, and the DTS writer has to
> relate the names to the actual clocks in the datasheet, and to the names
> used in the DT bindings for the consumer devices (if ever upstreamed),
> I find it hard to accept these for upstream inclusion as-is.
>
The other point I want to add is that the macros, which are designated
as reserved, have been included to prevent any breakage of ABI. In the
future, if we plan to add support for these IP blocks, these macros
will be renamed accordingly and utilized in the CPG driver.

Cheers,
Prabhakar

> What do other people think?
> Thanks!
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds