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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 May 2024 14:23:15 +0200
Message-ID: <CAMuHMdUJXdEG-BQRYNbmhbGCtE+O1uWO0j-PkBaF7S_Qyp8M-Q@mail.gmail.com>
Subject: Re: [PATCH v2 06/13] pinctrl: renesas: pinctrl-rzg2l: Add function
 pointers for locking/unlocking the PFC register
To: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Prabhakar <prabhakar.csengg@gmail.com>, Linus Walleij <linus.walleij@linaro.org>, 
	Rob Herring <robh@kernel.org>, Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley <conor+dt@kernel.org>, 
	Magnus Damm <magnus.damm@gmail.com>, 
	"linux-renesas-soc@vger.kernel.org" <linux-renesas-soc@vger.kernel.org>, 
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>, 
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, 
	Fabrizio Castro <fabrizio.castro.jz@renesas.com>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>
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Hi Biju,

On Tue, Apr 23, 2024 at 8:12=E2=80=AFPM Biju Das <biju.das.jz@bp.renesas.co=
m> wrote:
> > -----Original Message-----
> > From: Prabhakar <prabhakar.csengg@gmail.com>
> > Sent: Tuesday, April 23, 2024 6:59 PM
> > Subject: [PATCH v2 06/13] pinctrl: renesas: pinctrl-rzg2l: Add function=
 pointers for
> > locking/unlocking the PFC register
> >
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > On the RZ/G2L SoC, the PFCWE bit controls writing to PFC registers.
> > However, on the RZ/V2H(P) SoC, the PFCWE (REGWE_A on RZ/V2H) bit contro=
ls writing to both PFC and
> > PMC registers. Additionally, BIT(7) B0WI is undocumented for the PWPR r=
egister on RZ/V2H(P) SoC. To
> > accommodate these differences across SoC variants, introduce the set_pf=
c_mode() and
> > pm_set_pfc() function pointers.
> >
> > Note, in rzg2l_pinctrl_set_pfc_mode() the pwpr_pfc_unlock() call is now=
 called before PMC
> > read/write and pwpr_pfc_lock() call is now called after PMC read/write =
this is to keep changes
> > minimal for RZ/V2H(P).
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > ---
> > RFC->v2
> > - Introduced function pointer for (un)lock

> > --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > @@ -2688,6 +2699,8 @@ static struct rzg2l_pinctrl_data r9a07g043_data =
=3D {
> >       .variable_pin_cfg =3D r9a07g043f_variable_pin_cfg,
> >       .n_variable_pin_cfg =3D ARRAY_SIZE(r9a07g043f_variable_pin_cfg),
> >  #endif
> > +     .pwpr_pfc_unlock =3D &rzg2l_pwpr_pfc_unlock,
> > +     .pwpr_pfc_lock =3D &rzg2l_pwpr_pfc_lock,
> >  };
> >
> >  static struct rzg2l_pinctrl_data r9a07g044_data =3D { @@ -2699,6 +2712=
,8 @@ static struct
> > rzg2l_pinctrl_data r9a07g044_data =3D {
> >       .n_dedicated_pins =3D ARRAY_SIZE(rzg2l_dedicated_pins.common) +
> >               ARRAY_SIZE(rzg2l_dedicated_pins.rzg2l_pins),
> >       .hwcfg =3D &rzg2l_hwcfg,
> > +     .pwpr_pfc_unlock =3D &rzg2l_pwpr_pfc_unlock,
> > +     .pwpr_pfc_lock =3D &rzg2l_pwpr_pfc_lock,
> >  };
> >
> >  static struct rzg2l_pinctrl_data r9a08g045_data =3D { @@ -2709,6 +2724=
,8 @@ static struct
> > rzg2l_pinctrl_data r9a08g045_data =3D {
> >       .n_port_pins =3D ARRAY_SIZE(r9a08g045_gpio_configs) * RZG2L_PINS_=
PER_PORT,
> >       .n_dedicated_pins =3D ARRAY_SIZE(rzg3s_dedicated_pins),
> >       .hwcfg =3D &rzg3s_hwcfg,
> > +     .pwpr_pfc_unlock =3D &rzg2l_pwpr_pfc_unlock,
> > +     .pwpr_pfc_lock =3D &rzg2l_pwpr_pfc_lock,
>
> Some memory can be saved by avoiding duplication of data by using
> a single pointer for structure containing function pointers??
>
> struct rzg2l_pinctrl_fns {
>         void (*pwpr_pfc_unlock)(struct rzg2l_pinctrl *pctrl);
>         void (*pwpr_pfc_lock)(struct rzg2l_pinctrl *pctrl);
> }

So that would replace 3 (4 after adding RZ/V2H support) x 2 pointers in
rzg2l_pinctrl_data structures by 3 (4) pointers in rzg2l_pinctrl_data
structures + 1 (2) x 2 pointers in rzg2l_pinctrl_fns structures, and
code size would increase due to extra pointer dereferences before
each call.
Am I missing something?

Merging rzg2l_pwpr_pfc_{,un}lock() into a single function (taking a
"bool lock" flag) might be a better solution to reduce rzg2l_pinctrl_data s=
ize.

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds