RE: [PATCH net-next 03/18] drivers: clk: renesas: r9a07g044-cpg: Add ethernet clock sources

[Biju Das <biju.das.jz@bp.renesas.com>]

Hi Geert,

Thanks for the feedback.

> Subject: Re: [PATCH net-next 03/18] drivers: clk: renesas: r9a07g044-cpg:
> Add ethernet clock sources
> 
> Hi Biju,
> 
> On Thu, Jul 22, 2021 at 4:14 PM Biju Das <biju.das.jz@bp.renesas.com>
> wrote:
> > Ethernet reference clock can be sourced from PLL5_2 or PLL6_2. Add
> > support for ethernet source clock selection using SEL_PLL_6_2 mux.
> >
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/clk/renesas/r9a07g044-cpg.c
> > +++ b/drivers/clk/renesas/r9a07g044-cpg.c
> > @@ -35,8 +35,10 @@ enum clk_ids {
> >         CLK_PLL3_DIV4,
> >         CLK_PLL4,
> >         CLK_PLL5,
> > +       CLK_PLL5_2,
> 
> Why do you need this? We already have CLK_PLL5_DIV2?

As per clock list HP =250 MHz.

With PLL5_DIV2 the frequency, what we get is 3000 x 1/2 = 1500 MHz, which is incorrect

There is some issue with HW manual. It is not clear. I have requested to fix those issue.

Actually PLL5 generates 3 clk outputs (As per page 403 of manual)

FOUTPOSTDIV= 3000
FOUT3 = 500
FOUT1PH0 = 1500

To match the clock list document and Figure 8.3 Clock system diagram for HP clock.
This clock has to be FOUT3.

FOUT3(second PLL5 clock source)* 1/2 =250 MHz(HP clock).

On the HW manual, Divider name for PLL5 is mentioned as PLL_5_2_DIV12 and for PLL6 as PLL6_2_DIV2.

> 
> >         CLK_PLL5_DIV2,
> >         CLK_PLL6,
> > +       CLK_PLL6_DIV2,
> >         CLK_P1_DIV2,
> >
> >         /* Module Clocks */
> > @@ -53,6 +55,9 @@ static const struct clk_div_table dtable_1_32[] = {
> >         {0, 0},
> >  };
> >
> > +/* Mux clock tables */
> > +static const char * const sel_pll6_2[] = { ".pll6_2_div2",
> > +".pll5_2_div2" };
> 
> ".pll6_div2", ".pll5_div2"

Basically PLL6 generates 2 clock outputs. That is the reason it is termed as PLL6_2 for second clock
And pll5 generates 3 clock outputs and pll5_2(second clock source) is used for HP.

To match the register definition, I will change this to ".pll6_2_div2" and ".pll5_2_div12". Is it ok?

> 
> > +
> >  static const struct cpg_core_clk r9a07g044_core_clks[] __initconst = {
> >         /* External Clock Inputs */
> >         DEF_INPUT("extal", CLK_EXTAL), @@ -64,6 +69,11 @@ static const
> > struct cpg_core_clk r9a07g044_core_clks[] __initconst = {
> >         DEF_FIXED(".pll2", CLK_PLL2, CLK_EXTAL, 133, 2),
> >         DEF_FIXED(".pll3", CLK_PLL3, CLK_EXTAL, 133, 2),
> >
> > +       DEF_FIXED(".pll5", CLK_PLL5, CLK_EXTAL, 125, 1),
> > +       DEF_FIXED(".pll5_2", CLK_PLL5_2, CLK_PLL5, 1, 6),
> 
> Suffix "_2" but divided by 6?
> Why do you need this clock?

To generate 500 MHz Clock, so that it can match with clock list document.

> 
> > +
> > +       DEF_FIXED(".pll6", CLK_PLL6, CLK_EXTAL, 125, 6),
> > +
> >         DEF_FIXED(".pll2_div2", CLK_PLL2_DIV2, CLK_PLL2, 1, 2),
> >         DEF_FIXED(".pll2_div16", CLK_PLL2_DIV16, CLK_PLL2, 1, 16),
> >         DEF_FIXED(".pll2_div20", CLK_PLL2_DIV20, CLK_PLL2, 1, 20), @@
> > -73,6 +83,9 @@ static const struct cpg_core_clk r9a07g044_core_clks[]
> __initconst = {
> >         DEF_FIXED(".pll3_div2_4_2", CLK_PLL3_DIV2_4_2, CLK_PLL3_DIV2_4,
> 1, 2),
> >         DEF_FIXED(".pll3_div4", CLK_PLL3_DIV4, CLK_PLL3, 1, 4),
> >
> > +       DEF_FIXED(".pll5_2_div2", CLK_PLL5_DIV2, CLK_PLL5_2, 1, 2),
> 
> ".pll5_div2"
> Figure 8.3 ("Clock System Diagram (2)") says the parent is CLK_PLL5?

There is some issue in HW manual. Actually parent is second clock out from PLL5. See page 403.


> 
> > +       DEF_FIXED(".pll6_2_div2", CLK_PLL6_DIV2, CLK_PLL6, 1, 2),
> 
> ".pll6_div2"
> 
> > +
> >         /* Core output clk */
> >         DEF_FIXED("I", R9A07G044_CLK_I, CLK_PLL1, 1, 1),
> >         DEF_DIV("P0", R9A07G044_CLK_P0, CLK_PLL2_DIV16, DIVPL2A, @@
> > -83,6 +96,10 @@ static const struct cpg_core_clk r9a07g044_core_clks[]
> __initconst = {
> >         DEF_FIXED("P1_DIV2", CLK_P1_DIV2, R9A07G044_CLK_P1, 1, 2),
> >         DEF_DIV("P2", R9A07G044_CLK_P2, CLK_PLL3_DIV2_4_2,
> >                 DIVPL3A, dtable_1_32, CLK_DIVIDER_HIWORD_MASK),
> > +       DEF_FIXED("M0", R9A07G044_CLK_M0, CLK_PLL3_DIV2_4, 1, 1),
> > +       DEF_FIXED("ZT", R9A07G044_CLK_ZT, CLK_PLL3_DIV2_4_2, 1, 1),
> > +       DEF_MUX("HP", R9A07G044_CLK_HP, SEL_PLL6_2,
> > +               sel_pll6_2, ARRAY_SIZE(sel_pll6_2), 0,
> > + CLK_MUX_HIWORD_MASK),
> 
> OK.
> 
> >  };
> >
> >  static struct rzg2l_mod_clk r9a07g044_mod_clks[] = { diff --git
> > a/drivers/clk/renesas/rzg2l-cpg.h b/drivers/clk/renesas/rzg2l-cpg.h
> > index 148db5de253b..5202c0512483 100644
> > --- a/drivers/clk/renesas/rzg2l-cpg.h
> > +++ b/drivers/clk/renesas/rzg2l-cpg.h
> > @@ -11,6 +11,7 @@
> >
> >  #define CPG_PL2_DDIV           (0x204)
> >  #define CPG_PL3A_DDIV          (0x208)
> > +#define CPG_PL6_ETH_SSEL       (0x418)
> >
> >  /* n = 0/1/2 for PLL1/4/6 */
> >  #define CPG_SAMPLL_CLK1(n)     (0x04 + (16 * n))
> > @@ -24,6 +25,11 @@
> >  #define DIVPL3A                DDIV_PACK(CPG_PL3A_DDIV, 0, 3)
> >  #define DIVPL3B                DDIV_PACK(CPG_PL3A_DDIV, 4, 3)
> >
> > +#define SEL_PLL_PACK(offset, bitpos, size) \
> > +               (((offset) << 20) | ((bitpos) << 12) | ((size) << 8))
> 
> I think the addition of SEL_PLL_PACK() should be moved to [PATCH 02/18].
> 

OK.

Regards,
Biju

> > +
> > +#define SEL_PLL6_2     SEL_PLL_PACK(CPG_PL6_ETH_SSEL, 0, 1)
> > +
> >  /**
> >   * Definitions of CPG Core Clocks
> >   *
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> 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