From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Octavian Purdila <octavian.purdila@intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Lars-Peter Clausen <lars@metafoo.de>,
Robert Dolca <robert.dolca@gmail.com>,
Robert Dolca <robert.dolca@intel.com>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
Jonathan Cameron <jic23@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Hartmut Knaack <knaack.h@gmx.de>,
Peter Meerwald <pmeerw@pmeerw.net>,
Denis CIOCCA <denis.ciocca@st.com>
Subject: Re: [PATCH] IIO: Adds ACPI support for ST gyroscopes
Date: Fri, 27 Mar 2015 12:06:27 +0200 [thread overview]
Message-ID: <20150327100627.GW1878@lahna.fi.intel.com> (raw)
In-Reply-To: <CAE1zot+MaycNK91yOMLAfdvo=f21S9hts9ufk4krBMJ7PNYogA@mail.gmail.com>
On Thu, Mar 26, 2015 at 06:28:19PM +0200, Octavian Purdila wrote:
> >>> >> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> >>> >> index 568aa2b..9865627 100644
> >>> >> --- a/drivers/gpio/gpiolib.c
> >>> >> +++ b/drivers/gpio/gpiolib.c
> >>> >> @@ -511,6 +511,19 @@ static const struct irq_domain_ops gpiochip_domain_ops = {
> >>> >> static int gpiochip_irq_reqres(struct irq_data *d)
> >>> >> {
> >>> >> struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
> >>> >> + int ret;
> >>> >> +
> >>> >> + ret = gpiod_request(&chip->desc[d->hwirq], "IRQ");
> >>> >> + if (ret) {
> >>> >> + chip_err(chip, "unable to request %lu for IRQ\n", d->hwirq);
> >>> >> + return ret;
> >>> >> + }
> >>> >
> >>> > What if the driver has already requested the GPIO?
> >>> >
> >>>
> >>> Initially I implemented the above to take that into account, e.g. if
> >>> (test_and_set_bit(FLAG_REQUESTED, &desc->flags) ...
> >>>
> >>> But than I thought that we can't mess up with the GPIO anyway while
> >>> the interrupt is in use.
> >>
> >> That's right but then the above will fail also normal cases. For example
> >> if the driver gets the irq like:
> >>
> >> desc = devm_gpiod_get(dev, ..);
> >> gpiod_direction_input(desc);
> >> irq = gpiod_to_irq(desc);
> >>
> >> ret = request_irq(irq, ...)
> >>
> >> at this point we end up calling gpiochip_irq_reqres() which cannot
> >> request the GPIO again and fails.
> >>
> >
> > Good point, let me add back that check then :)
> >
>
> I just realized that there is another issue: gpiochip_irq_reqres() is
> called under a spinlock, so we can call gpiod_request() only if the
> gpio controller does not sleep.
Good point.
> For the sleep case I think the GPIO controller needs to do the pin
> enable and set input direction operation in it's irq_bus_sync_unlock.
I wonder how DT handles all this? Is it the boot firmware that sets up
the pins accordingly or is there something we are missing?
next prev parent reply other threads:[~2015-03-27 10:06 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-23 13:40 [PATCH] IIO: Adds ACPI support for ST gyroscopes Robert Dolca
2015-03-23 13:40 ` [PATCH] IIO: Add support for L3GD20H gyroscope Robert Dolca
2015-03-24 10:29 ` Linus Walleij
2015-03-28 11:14 ` Jonathan Cameron
2015-03-23 15:18 ` [PATCH] IIO: Adds ACPI support for ST gyroscopes Mika Westerberg
2015-03-24 11:51 ` Daniel Baluta
2015-03-24 10:22 ` Linus Walleij
2015-03-24 10:37 ` Linus Walleij
2015-03-24 10:44 ` Linus Walleij
2015-03-24 12:17 ` Lars-Peter Clausen
2015-03-24 13:26 ` Robert Dolca
2015-03-24 13:38 ` Lars-Peter Clausen
2015-03-24 13:57 ` Linus Walleij
2015-03-24 15:06 ` Mika Westerberg
2015-03-24 15:22 ` Lars-Peter Clausen
2015-03-24 15:28 ` Daniel Baluta
2015-03-24 15:55 ` Mika Westerberg
2015-03-24 16:43 ` Lars-Peter Clausen
2015-03-24 16:55 ` Mika Westerberg
2015-03-25 8:44 ` Linus Walleij
2015-03-25 9:43 ` Mika Westerberg
2015-03-25 12:25 ` Mika Westerberg
2015-03-25 13:21 ` Mika Westerberg
2015-03-25 13:42 ` Robert Dolca
2015-03-25 18:05 ` sathyanarayanan kuppuswamy
2015-03-25 18:08 ` Lars-Peter Clausen
2015-03-25 21:12 ` Octavian Purdila
2015-03-26 10:06 ` Robert Dolca
2015-03-26 10:36 ` Mika Westerberg
2015-03-26 10:16 ` Mika Westerberg
2015-03-26 12:04 ` Octavian Purdila
2015-03-26 14:04 ` Mika Westerberg
2015-03-26 14:37 ` Octavian Purdila
2015-03-26 14:47 ` Mika Westerberg
2015-03-26 15:00 ` Octavian Purdila
2015-03-26 16:28 ` Octavian Purdila
2015-03-27 10:06 ` Mika Westerberg [this message]
2015-03-27 10:36 ` Linus Walleij
2015-03-30 9:52 ` Mika Westerberg
2015-03-30 12:55 ` Octavian Purdila
2015-03-30 13:33 ` Mika Westerberg
2015-03-30 13:52 ` Octavian Purdila
2015-03-30 14:18 ` Mika Westerberg
2015-04-07 9:35 ` Linus Walleij
2015-04-07 9:39 ` Lars-Peter Clausen
2015-03-26 18:32 ` Jonathan Cameron
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