linux-kernel - Re: [PATCH v2 2/2] clk: renesas: r9a09g077: Add Ethernet Subsystem core and module clocks

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Message-ID: <CA+V-a8t1PDpqqMAdWxPeQfH6MWQe0GHsuBSzRbaRFRPPMf_iQA@mail.gmail.com>
Date: Tue, 2 Sep 2025 16:05:44 +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>, 
	Magnus Damm <magnus.damm@...il.com>, linux-renesas-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v2 2/2] clk: renesas: r9a09g077: Add Ethernet Subsystem
 core and module clocks

Hi Geert,

Thank you for the review.

On Tue, Sep 2, 2025 at 2:01 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Mon, 1 Sept 2025 at 20:30, Prabhakar <prabhakar.csengg@...il.com> wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Add module and core clocks used by Ethernet Subsystem (Ethernet_SS),
> > Ethernet MAC (GMAC), Ethernet Switch (ETHSW).
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Thanks for your patch!
>
> > --- a/drivers/clk/renesas/r9a09g077-cpg.c
> > +++ b/drivers/clk/renesas/r9a09g077-cpg.c
> > @@ -72,7 +72,7 @@ enum rzt2h_clk_types {
> >
> >  enum clk_ids {
> >         /* Core Clock Outputs exported to DT */
> > -       LAST_DT_CORE_CLK = R9A09G077_USB_CLK,
> > +       LAST_DT_CORE_CLK = R9A09G077_GMAC2_PCLKAH,
> >
> >         /* External Input Clocks */
> >         CLK_EXTAL,
> > @@ -166,11 +166,21 @@ static const struct cpg_core_clk r9a09g077_core_clks[] __initconst = {
> >         DEF_DIV("CA55S", R9A09G077_CLK_CA55S, CLK_SEL_CLK_PLL0, DIVCA55S,
> >                 dtable_1_2),
> >         DEF_FIXED("PCLKGPTL", R9A09G077_CLK_PCLKGPTL, CLK_SEL_CLK_PLL1, 2, 1),
> > +       DEF_FIXED("PCLKH", R9A09G077_CLK_PCLKH, CLK_SEL_CLK_PLL1, 4, 1),
> >         DEF_FIXED("PCLKM", R9A09G077_CLK_PCLKM, CLK_SEL_CLK_PLL1, 8, 1),
> >         DEF_FIXED("PCLKL", R9A09G077_CLK_PCLKL, CLK_SEL_CLK_PLL1, 16, 1),
> > +       DEF_FIXED("PCLKAH", R9A09G077_CLK_PCLKAH, CLK_PLL4D1, 6, 1),
> >         DEF_FIXED("PCLKAM", R9A09G077_CLK_PCLKAM, CLK_PLL4D1, 12, 1),
> >         DEF_FIXED("SDHI_CLKHS", R9A09G077_SDHI_CLKHS, CLK_SEL_CLK_PLL2, 1, 1),
> >         DEF_FIXED("USB_CLK", R9A09G077_USB_CLK, CLK_PLL4D1, 48, 1),
> > +       DEF_FIXED("ETCLKA", R9A09G077_ETCLKA, CLK_SEL_CLK_PLL1, 5, 1),
> > +       DEF_FIXED("ETCLKB", R9A09G077_ETCLKB, CLK_SEL_CLK_PLL1, 8, 1),
> > +       DEF_FIXED("ETCLKC", R9A09G077_ETCLKC, CLK_SEL_CLK_PLL1, 10, 1),
> > +       DEF_FIXED("ETCLKD", R9A09G077_ETCLKD, CLK_SEL_CLK_PLL1, 20, 1),
> > +       DEF_FIXED("ETCLKE", R9A09G077_ETCLKE, CLK_SEL_CLK_PLL1, 40, 1),
> > +       DEF_FIXED("GMAC0_PCLKH", R9A09G077_GMAC0_PCLKH, R9A09G077_CLK_PCLKH, 1, 1),
> > +       DEF_FIXED("GMAC1_PCLKH", R9A09G077_GMAC1_PCLKAH, R9A09G077_CLK_PCLKAH, 1, 1),
> > +       DEF_FIXED("GMAC2_PCLKH", R9A09G077_GMAC2_PCLKAH, R9A09G077_CLK_PCLKAH, 1, 1),
>
> Do you need these? I can't seem to find them in the documentation,
> so they are not just for aiding the casual reader.  As their
> multipliers/dividers are 1/1, you can just use R9A09G077_CLK_PCLKH
> resp. R9A09G077_CLK_PCLKAH in the DTS?
>
Agreed, we can get rid of these and just use R9A09G077_CLK_PCLK{A}H in
the SoC DTSI.

> >  };
> >
> >  static const struct mssr_mod_clk r9a09g077_mod_clks[] __initconst = {
> > @@ -181,7 +191,12 @@ static const struct mssr_mod_clk r9a09g077_mod_clks[] __initconst = {
> >         DEF_MOD("sci4fck", 12, CLK_SCI4ASYNC),
> >         DEF_MOD("iic0", 100, R9A09G077_CLK_PCLKL),
> >         DEF_MOD("iic1", 101, R9A09G077_CLK_PCLKL),
> > +       DEF_MOD("gmac0", 400, R9A09G077_CLK_PCLKM),
> > +       DEF_MOD("ethsw", 401, R9A09G077_CLK_PCLKM),
>
> According to Table 7.13 ("Overview of Clock Generation Circuit
> Specifications (Internal Clock)"), ETCLKA is used as the operating
> clock for ETHSW?
>
There are 3 clock inputs to ETHSW,
- PCLKM -  bus clock
- ETCLKA - operating clock
- ETCLKB - Ts clock

Based on Documentation/devicetree/bindings/net/dsa/renesas,rzn1-a5psw.yaml
we have two clocks for RZ/N1 (Ts clock is missing)
- description: AHB clock used for the switch register interface
- description: Switch system clock

- const: hclk
- const: clk

So I was treating,
- hclk -> PCLKM,
- clk   -> ETCLKA
- ts    -> ETCLKB

Since pclkm is used for register access, I added this entry to the
r9a09g077_mod_clks array as I was under the impression the clocks used
for reg access need to go into this array.

> > +       DEF_MOD("ethss", 403, R9A09G077_CLK_PCLKM),
> >         DEF_MOD("usb", 408, R9A09G077_CLK_PCLKAM),
> > +       DEF_MOD("gmac1", 416, R9A09G077_CLK_PCLKAM),
> > +       DEF_MOD("gmac2", 417, R9A09G077_CLK_PCLKAM),
> >         DEF_MOD("sci5fck", 600, CLK_SCI5ASYNC),
> >         DEF_MOD("iic2", 601, R9A09G077_CLK_PCLKL),
> >         DEF_MOD("sdhi0", 1212, R9A09G077_CLK_PCLKAM),
>
> The rest LGTM.  But as the full wiring is not clear to me, I guess
> I'll have to wait for the DTS...
>
I'll soon post the Ethernet enabling patches.

Cheers,
Prabhakar