linux-kernel - Re: [PATCH] IIO: Adds ACPI support for ST gyroscopes

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Message-ID: <CAE1zotJas26oRGdext7V69mNNyaYT3Ds7+Ruhg_kNKBf-Ewoew@mail.gmail.com>
Date:	Wed, 25 Mar 2015 23:12:16 +0200
From:	Octavian Purdila <octavian.purdila@...el.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Robert Dolca <robert.dolca@...il.com>,
	Robert Dolca <robert.dolca@...el.com>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	Jonathan Cameron <jic23@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Denis CIOCCA <denis.ciocca@...com>
Subject: Re: [PATCH] IIO: Adds ACPI support for ST gyroscopes

On Wed, Mar 25, 2015 at 3:21 PM, Mika Westerberg
<mika.westerberg@...ux.intel.com> wrote:
> On Wed, Mar 25, 2015 at 02:25:05PM +0200, Mika Westerberg wrote:
>> I think we can do the same for ACPI GpioInts so that we introduce
>> acpi_gpio_irq_get() that translates from GpioInt to Linux IRQ
>> numberspace. Then we can do something like below in I2C core:
>>
>>       if (client->irq <= 0) {
>>               int irq = -ENOENT;
>>
>>                 if (dev->of_node)
>>                         irq = of_irq_get(dev->of_node, 0);
>>                 else if (ACPI_COMPANION(dev))
>>                         irq = acpi_gpio_irq_get(ACPI_COMPANION(dev), 0);
>>
>>               if (irq == -EPROBE_DEFER)
>>                         return irq;
>>                 if (irq < 0)
>>                         irq = 0;
>>
>>                 client->irq = irq;
>>       }
>>
>> Now it has the drawback that the first GpioInt will not be available to
>> the driver anymore (as a GPIO since it is locked) but if DT already does
>> the same we should be fine.
>
> Below patch should take care of this.
>

One issue we noticed is that now the gpio request and set input
directions operations are not called anymore. Some gpio controller
drivers (dln2, adnp, lynx_point from quickly browsing the code) do not
explicitly enable the GPIO pin nor set direction to input when the
interrupt is enabled. Depending on hardware this may be an issue - it
is on dln2 for example.

Should the gpio controllers enable and set to input in irq_enable,
irq_bus_sync_unlock, etc.? Or should this be done in gpiolib?
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