From: Horatiu Vultur <horatiu.vultur@microchip.com>
To: Michael Walle <michael@walle.cc>
Cc: <UNGLinuxDriver@microchip.com>, <andy.shevchenko@gmail.com>,
<linus.walleij@linaro.org>, <linux-gpio@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] pinctrl: ocelot: Fix interrupt controller
Date: Thu, 13 Oct 2022 16:11:49 +0200 [thread overview]
Message-ID: <20221013141149.zrcdtcfragerxdyw@soft-dev3-1> (raw)
In-Reply-To: <994b3dfd8d5d2c0c11c2bf6f299564c1@walle.cc>
The 10/13/2022 09:30, Michael Walle wrote:
Hi Michael,
> > We lose the interrupt here, as the HW will not generate another one
> > but at later point we read again the line status. And if the line is
> > active then we kick again the interrupt handler again.
>
> Ahh, thanks for explaining. That also explains the read below.
>
> Will you send a proper patch?
No worries. Yes, I will do that.
>
> -michael
>
> >
> > >
> > > > +
> > > > /* Enable the interrupt now */
> > > > gpiochip_enable_irq(chip, gpio);
> > > > regmap_update_bits(info->map, REG(OCELOT_GPIO_INTR_ENA, info, gpio),
> > > > bit, bit);
> > > >
> > > > /*
> > > > - * In case the interrupt line is still active and the interrupt
> > > > - * controller has not seen any changes in the interrupt line, then it
> > > > - * means that there happen another interrupt while the line was
> > > > active.
> > > > + * In case the interrupt line is still active then it means that
> > > > + * there happen another interrupt while the line was active.
> > > > * So we missed that one, so we need to kick the interrupt again
> > > > * handler.
> > > > */
> > > > - if (active && !ack) {
> > > > + regmap_read(info->map, REG(OCELOT_GPIO_IN, info, gpio), &val);
> > > > + if ((!(val & bit) && trigger_level == IRQ_TYPE_LEVEL_LOW) ||
> > > > + (val & bit && trigger_level == IRQ_TYPE_LEVEL_HIGH))
> > > > + active = true;
> > >
> > > Why do you read the line state twice? What happens if the line state
> > > changes right after you've read it?
> >
> > Here we need to read again the status because we might have clear the
> > ack of interrupt.
> > If the line becomes active right after this read, then the HW will
> > generate another interrupt as the interrupt is enabled and ack is
> > cleared.
> >
> > >
> > > > +
> > > > + if (active) {
> > > > struct ocelot_irq_work *work;
> > > >
> > > > work = kmalloc(sizeof(*work), GFP_ATOMIC);
> > >
> > > So yes, maybe the trade-off that there will be two interrupts are
> > > better than this additional patch. But it should be documented
> > > somewhere, even if it's just a comment in this driver.
> > >
> > > -michael
--
/Horatiu
prev parent reply other threads:[~2022-10-13 14:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-09 14:59 [PATCH v3] pinctrl: ocelot: Fix interrupt controller Horatiu Vultur
2022-09-09 15:09 ` Andy Shevchenko
2022-09-15 11:33 ` Horatiu Vultur
2022-09-14 13:02 ` Linus Walleij
2022-09-15 11:22 ` Horatiu Vultur
2022-09-18 18:55 ` Linus Walleij
2022-09-20 12:06 ` Michael Walle
2022-09-20 12:28 ` Linus Walleij
2022-09-20 12:34 ` Michael Walle
2022-09-20 14:25 ` Michael Walle
2022-09-20 19:30 ` Horatiu Vultur
2022-10-06 11:43 ` Michael Walle
2022-10-07 9:49 ` Horatiu Vultur
2022-10-13 7:30 ` Michael Walle
2022-10-13 14:11 ` Horatiu Vultur [this message]
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