From: Stephen Boyd <swboyd@chromium.org>
To: Maulik Shah <mkshah@codeaurora.org>,
bjorn.andersson@linaro.org, evgreen@chromium.org,
linus.walleij@linaro.org, maz@kernel.org, mka@chromium.org
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-gpio@vger.kernel.org, agross@kernel.org,
tglx@linutronix.de, jason@lakedaemon.net, dianders@chromium.org,
rnayak@codeaurora.org, ilina@codeaurora.org,
lsrao@codeaurora.org
Subject: Re: [PATCH v2 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable
Date: Wed, 27 May 2020 18:08:46 -0700 [thread overview]
Message-ID: <159062812628.69627.2153485337510882984@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <4e070cda-8c22-c554-610e-172320045840@codeaurora.org>
Quoting Maulik Shah (2020-05-27 04:26:14)
> On 5/27/2020 3:14 PM, Stephen Boyd wrote:
> > Quoting Maulik Shah (2020-05-23 10:11:10)
> >> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> >> index eaa0e20..3810cd0 100644
> >> --- a/drivers/gpio/gpiolib.c
> >> +++ b/drivers/gpio/gpiolib.c
> >> @@ -2465,32 +2465,37 @@ static void gpiochip_irq_relres(struct irq_data *d)
> >> gpiochip_relres_irq(gc, d->hwirq);
> >> }
> >>
> >> +static void gpiochip_irq_mask(struct irq_data *d)
> >> +{
> >> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> >> +
> >> + if (gc->irq.irq_mask)
> >> + gc->irq.irq_mask(d);
> >> + gpiochip_disable_irq(gc, d->hwirq);
> > How does this work in the lazy case when I want to drive the GPIO? Say I
> > have a GPIO that is also an interrupt. The code would look like
> >
> > struct gpio_desc *gpio = gpiod_get(...)
> > unsigned int girq = gpiod_to_irq(gpio)
> >
> > request_irq(girq, ...);
> >
> > disable_irq(girq);
> > gpiod_direction_output(gpio, 1);
> >
> > In the lazy case genirq wouldn't call the mask function until the first
> > interrupt arrived on the GPIO line. If that never happened then wouldn't
> > we be blocked in gpiod_direction_output() when the test_bit() sees
> > FLAG_USED_AS_IRQ? Or do we need irqs to be released before driving
> > gpios?
>
> The client driver can decide to unlazy disable IRQ with below API...
>
> irq_set_status_flags(girq, IRQ_DISABLE_UNLAZY);
>
> This will immediatly invoke mask function (unlazy disable) from genirq,
> even though irq_disable is not implemented.
>
Sure a consumer can disable the lazy feature, but that shouldn't be
required to make this work. The flag was introduced in commit
e9849777d0e2 ("genirq: Add flag to force mask in
disable_irq[_nosync]()") specifically to help devices that can't disable
the interrupt in their own device avoid a double interrupt.
next prev parent reply other threads:[~2020-05-28 1:08 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-23 17:11 [PATCH v2 0/4] irqchip: qcom: pdc: Introduce irq_set_wake call Maulik Shah
2020-05-23 17:11 ` [PATCH v2 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable Maulik Shah
2020-05-25 11:55 ` Linus Walleij
2020-05-25 12:22 ` Hans Verkuil
2020-05-26 4:45 ` Maulik Shah
2020-05-27 10:38 ` Hans Verkuil
2020-05-27 13:56 ` Linus Walleij
2020-05-27 14:15 ` Russell King - ARM Linux admin
2020-05-27 9:44 ` Stephen Boyd
2020-05-27 11:26 ` Maulik Shah
2020-05-28 1:08 ` Stephen Boyd [this message]
2020-05-28 13:11 ` Maulik Shah
2020-05-28 22:22 ` Stephen Boyd
2020-05-29 9:57 ` Maulik Shah
2020-05-28 21:33 ` Linus Walleij
[not found] ` <159070486671.69627.662167272601689396@swboyd.mtv.corp.google.com>
2020-06-03 12:28 ` Linus Walleij
2020-05-23 17:11 ` [PATCH v2 2/4] pinctrl: qcom: Remove irq_disable callback from msmgpio irqchip Maulik Shah
2020-05-23 17:11 ` [PATCH v2 3/4] pinctrl: qcom: Add msmgpio irqchip flags Maulik Shah
2020-05-27 9:47 ` Stephen Boyd
2020-05-27 12:30 ` Maulik Shah
2020-05-23 17:11 ` [PATCH v2 4/4] irqchip: qcom-pdc: Introduce irq_set_wake call Maulik Shah
2020-05-27 10:15 ` Stephen Boyd
2020-05-29 9:20 ` Maulik Shah
2020-05-30 19:26 ` Stephen Boyd
2020-06-01 11:38 ` Maulik Shah
2020-06-16 11:57 ` Stephen Boyd
2020-06-18 10:03 ` Maulik Shah
2020-06-19 9:26 ` Stephen Boyd
2020-06-22 9:19 ` Maulik Shah
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