linux-kernel - Re: [PATCH 3/3] HID: i2c-hid: Add support for ACPI GPIO interrupts

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Message-ID: <20150225080211.GM1758@lahna.fi.intel.com>
Date:	Wed, 25 Feb 2015 10:02:11 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Antonio Ospite <ao2@....it>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	Mark Rutland <mark.rutland@....com>, sb@...abs.hk,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] HID: i2c-hid: Add support for ACPI GPIO interrupts

On Tue, Feb 24, 2015 at 10:27:05PM +0100, Antonio Ospite wrote:
> On Mon, 23 Feb 2015 15:52:45 +0200
> Mika Westerberg <mika.westerberg@...ux.intel.com> wrote:
> 
> > The HID over I2C specification allows to have the interrupt for a HID
> > device to be GPIO instead of directly connected to the IO-APIC.
> > 
> > Add support for this so that when the driver does not find proper interrupt
> > number from the I2C client structure we check if it has ACPI GpioInt()
> > resource listed in _CRS. If it is found we convert it to an interrupt
> > number and use it instead.
> > 
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> > ---
> >  drivers/hid/i2c-hid/i2c-hid.c | 68 +++++++++++++++++++++++++++++++------------
> >  1 file changed, 50 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> > index 404ccde49acd..c6cad72f6296 100644
> > --- a/drivers/hid/i2c-hid/i2c-hid.c
> > +++ b/drivers/hid/i2c-hid/i2c-hid.c
> > @@ -37,6 +37,7 @@
> >  #include <linux/mutex.h>
> >  #include <linux/acpi.h>
> >  #include <linux/of.h>
> > +#include <linux/gpio/consumer.h>
> >  
> >  #include <linux/i2c/i2c-hid.h>
> >  
> > @@ -144,6 +145,8 @@ struct i2c_hid {
> >  	unsigned long		flags;		/* device flags */
> >  
> >  	wait_queue_head_t	wait;		/* For waiting the interrupt */
> > +	struct gpio_desc	*desc;
> 
> Just curious: can't the gpio_desc be local in the probe function?
> I take that the gpio descriptor needs to be alive even after the irq
> number has been derived from it in order for the gpio chip to remember
> that the gpio has been requested by someone. Is that correct?

That's right and we need to release it in remove() as well.

Someone should convert this driver to use devm_* APIs...
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