linux-kernel - Re: [PATCH RESEND] pinctrl: mediatek: Fix trigger type setting follow for unexpected interrupt

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Message-ID: <CANMq1KCXrEGrNrOwivrchXyawzKySVzQoxA1goYC-eh-auNFCA@mail.gmail.com>
Date:   Thu, 21 Jan 2021 20:13:16 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     mtk15103 <hailong.fan@...iatek.com>
Cc:     Sean Wang <sean.wang@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>, youlin.pei@...iatek.com,
        srv_heupstream <srv_heupstream@...iatek.com>,
        Chen-Tsung Hsieh <chentsung@...omium.org>,
        gtk_pangao@...iatek.com, Hanks Chen <hanks.chen@...iatek.com>,
        Yong Wu <yong.wu@...iatek.com>
Subject: Re: [PATCH RESEND] pinctrl: mediatek: Fix trigger type setting follow
 for unexpected interrupt

On Thu, Jan 21, 2021 at 8:09 PM mtk15103 <hailong.fan@...iatek.com> wrote:
>
> On Thu, 2021-01-21 at 16:55 +0800, Nicolas Boichat wrote:
> > On Thu, Jan 21, 2021 at 3:52 PM Hailong Fan <hailong.fan@...iatek.com> wrote:
> > >
> > > When flipping the polarity will be generated interrupt under certain
> > > circumstances, but GPIO external signal has not changed.
> > > Then, mask the interrupt before polarity setting, and clear the
> > > unexpected interrupt after trigger type setting completed.
> > >
> > > Signed-off-by: Hailong Fan <hailong.fan@...iatek.com>
> > > ---
> > > Resend since some server reject.
> > > ---
> > >  drivers/pinctrl/mediatek/mtk-eint.c | 13 +++++++++++--
> > >  1 file changed, 11 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/pinctrl/mediatek/mtk-eint.c b/drivers/pinctrl/mediatek/mtk-eint.c
> > > index 22736f60c16c..3acda6bb401e 100644
> > > --- a/drivers/pinctrl/mediatek/mtk-eint.c
> > > +++ b/drivers/pinctrl/mediatek/mtk-eint.c
> > > @@ -157,6 +157,7 @@ static void mtk_eint_ack(struct irq_data *d)
> > >  static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
> > >  {
> > >         struct mtk_eint *eint = irq_data_get_irq_chip_data(d);
> > > +       unsigned int unmask;
> >
> > bool?
> Yes,thanks.
> >
> > >         u32 mask = BIT(d->hwirq & 0x1f);
> > >         void __iomem *reg;
> > >
> > > @@ -173,6 +174,13 @@ static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
> > >         else
> > >                 eint->dual_edge[d->hwirq] = 0;
> > >
> > > +       if (!mtk_eint_get_mask(eint, d->hwirq)) {
> > > +               mtk_eint_mask(d);
> > > +               unmask = 1;
> > > +       } else {
> > > +               unmask = 0;
> > > +       }
> > > +
> > >         if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_EDGE_FALLING)) {
> > >                 reg = mtk_eint_get_offset(eint, d->hwirq, eint->regs->pol_clr);
> > >                 writel(mask, reg);
> > > @@ -189,8 +197,9 @@ static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
> > >                 writel(mask, reg);
> > >         }
> > >
> > > -       if (eint->dual_edge[d->hwirq])
> > > -               mtk_eint_flip_edge(eint, d->hwirq);
> >
> > Why are you dropping this? Aren't we at risk to miss the first edge
> > after mtk_eint_set_type is called?
> mtk_eint_unmask() will do it.
> If unmask != 1, user need to call mtk_eint_unmask() to enable the
> interrupt before use it, thanks.

Makes sense, I just have one more worry:
https://elixir.bootlin.com/linux/latest/source/drivers/pinctrl/mediatek/mtk-eint.c#L122

mtk_eint_unmask unmasks the interrupt _before_ the edge is flipped,
could this cause a spurious interrupt? On any unmask operation -- not
just on mtk_eint_set_type (so this is technically another problem,
that should be fixed as a separate patch)

> > > +       mtk_eint_ack(d);
> > > +       if (unmask == 1)
> >
> > Just `if (unmask)`
> Yes,thanks.
> > > +               mtk_eint_unmask(d);
> > >
> > >         return 0;
> > >  }
> > > --
> > > 2.18.0
>