linux-kernel - Re: [PATCH 2/2] pinctrl: renesas: rzg2l: Enable noise filter for GPIO interrupt input

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Message-ID: <CAMuHMdWtHawgor2Hs3vZDcTv8WXWhUAzSRYBpM1cD=ozKT4G2w@mail.gmail.com>
Date:   Mon, 18 Sep 2023 15:25:54 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Claudiu Beznea <claudiu.beznea.uj@...renesas.com>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        Marc Zyngier <maz@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Biju Das <biju.das.au@...il.com>
Subject: Re: [PATCH 2/2] pinctrl: renesas: rzg2l: Enable noise filter for GPIO
 interrupt input

Hi Biju,

On Mon, Sep 18, 2023 at 3:18 PM Biju Das <biju.das.jz@...renesas.com> wrote:
> > Subject: Re: [PATCH 2/2] pinctrl: renesas: rzg2l: Enable noise filter for
> > GPIO interrupt input
> >
> > On Mon, Sep 18, 2023 at 2:34 PM Biju Das <biju.das.jz@...renesas.com>
> > wrote:
> > > As per RZ/G2L hardware manual Rev.1.30 section 8.7.3 GPIO Interrupt
> > > (TINT) and 41.4.1 Operation for GPIO function, we need to set digital
> > > noise filter for GPIO interrupt.
> > >
> > > This patch enables noise filter for GPIO interrupt in
> > > rzg2l_gpio_irq_enable() and disable it in rzg2l_gpio_irq_disable().
> > >
> > > Fixes: db2e5f21a48e ("pinctrl: renesas: pinctrl-rzg2l: Add IRQ domain
> > > to handle GPIO interrupt")
> > > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> > > Tested-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > @@ -96,6 +96,7 @@
> > >  #define PIN(n)                 (0x0800 + 0x10 + (n))
> > >  #define IOLH(n)                        (0x1000 + (n) * 8)
> > >  #define IEN(n)                 (0x1800 + (n) * 8)
> > > +#define FILONOFF(n)            (0x2080 + (n) * 8)
> > >  #define ISEL(n)                        (0x2c80 + (n) * 8)
> > >  #define PWPR                   (0x3014)
> > >  #define SD_CH(n)               (0x3000 + (n) * 4)
> >
> > LGTM, but shouldn't you configure the Digital Noise Filter Number
> > (FILNUM) and Clock Selection (FILCLKSEL) registers, too?
>
> Currently it uses reset values.
>
> 00b: 4-stage filter (41.666 ns x 4 = 166.666 ns) (initial value) for FILNUM and
>
> 00b: Not divided (initial value) for FILCLKSEL
>
> Do you mean we should provide these settings to DT, so that
> it is customised based on the PCB design and the environment
> the board is used in? I guess this will make it easier for
> customers to make the required changes for their application.

If the optimal values are board-dependent, you should indeed add
a way to configure this from DT.

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