On Mon, Jan 26, 2015 at 04:13:56PM +0000, Mika Westerberg wrote: > On Mon, Jan 26, 2015 at 04:01:20PM +0000, Mark Rutland wrote: > > On Mon, Jan 26, 2015 at 03:16:37PM +0000, Mika Westerberg wrote: > > > On Mon, Jan 26, 2015 at 02:50:01PM +0000, Mark Rutland wrote: > > > > On Mon, Jan 26, 2015 at 02:47:29PM +0000, Mika Westerberg wrote: > > > > > On Mon, Jan 26, 2015 at 02:37:24PM +0000, Mark Rutland wrote: > > > > > > On Mon, Jan 26, 2015 at 02:29:33PM +0000, Mika Westerberg 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 the device has property > > > > > > > named "gpios". This is then assumed to be the GPIO that serves as an > > > > > > > interrupt for the device. > > > > > > > > > > > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > > > > > --- > > > > > > > .../devicetree/bindings/hid/hid-over-i2c.txt | 5 +- > > > > > > > drivers/hid/i2c-hid/i2c-hid.c | 70 ++++++++++++++++------ > > > > > > > 2 files changed, 56 insertions(+), 19 deletions(-) > > > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/hid/hid-over-i2c.txt b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt > > > > > > > index 488edcb264c4..8f4a99dad3b9 100644 > > > > > > > --- a/Documentation/devicetree/bindings/hid/hid-over-i2c.txt > > > > > > > +++ b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt > > > > > > > @@ -15,7 +15,10 @@ Required properties: > > > > > > > - reg: i2c slave address > > > > > > > - hid-descr-addr: HID descriptor address > > > > > > > - interrupt-parent: the phandle for the interrupt controller > > > > > > > -- interrupts: interrupt line > > > > > > > +- interrupts: interrupt line if the device uses IO-APIC interrupts > > > > > > > + > > > > > > > +Optional properties: > > > > > > > +- gpios: GPIO used as an interrupt if the device uses GPIO interrupts > > > > > > > > > > > > Elsewhere we've said that for a GPIO acting as an interrupt line, GPIO > > > > > > controller should be marked as an interrupt-controller, and the GPIO > > > > > > described as an interrupt line. That also gets you the appropriate > > > > > > configuration for the GPIO as an interrupt. > > > > > > > > > > > > Does this GPIO serve any other purpose than an ersatz interrupt line? > > > > > > > > > > It is just an interrupt. > > > > > > > > > > > If not, it should probably be described as an interrupt. From the PoV of > > > > > > this device, it's just an interrupt controller hooked up to the > > > > > > interrupt pin. > > > > > > > > > > What I'm trying to do is to get a GPIO that is described in ACPI (as > > > > > GpioInt() in _CRS) to be supported in this driver using gpiolib like > > > > > this: > > > > > > > > > > desc = gpiod_get(&client->dev, NULL); > > > > > > > > > > This calls to find "gpios" property which ends up finding the GpioInt() > > > > > in _CRS. > > > > > > > > I understand what you are trying to do, but I disagree on the principle. > > > > If it's logically an interrupt, it should be described as an interrupt. > > > > > > It is a GPIO line that is used as interrupt. It is not IO-APIC interrupt > > > or anything like that. It will be handled through a GPIO driver. > > > > I understand that the interrupt line is wired up to a GPIO controller, > > where the GPIO controller is able to raise an interrupt as required. > > > > However, from the PoV of the I2C device, this doesn't matter. From it's > > PoV it raises an interrupt, and that's all. It has no idea what happens > > to be wired up to its IRQ pin, and nor should it. > > > > > > If ACPI lacks the ability to describe things in that fashion, it's yet > > > > another reason that we shouldn't be pretending that DT and ACPI are the > > > > same thing. > > > > > > I'm not saying they are the same thing (they're not). I'm trying to get > > > a GPIO from ACPI translated to an interrupt so that the driver can use > > > it. Preferably so that the DT description does not prevent people from > > > using the same on non-ACPI platforms. > > > > If you're following the Microsoft HID over I2C ACPI spec, why is this DT > > binding document relevant. Assuming you're following the spec, you won't > > be using _DSD with "hid-over-i2c". If you're not following the spec then > > you aren't following the spec, so the spec is irrelevant. > > > > > ACPI can desribe Interrupt(), GpioInt() and GpioIo() just fine. It is > > > the Microsoft HID over I2C specification that says it should be > > > GpioInt() even though we have seen Interrupt() used there as well. > > > > Ok, so if the HID over I2C spec says that for ACPI, do that for ACPI. > > > > I don't follow why the DT binding should do this. > > I added it there because I thought it's the right thing to do. After all > it is assumed that there exists property "gpios" now for both ACPI and > DT if I pass NULL in gpiod_get(). That's not great. Now we have ACPI and DT concerns leaking into each other when they shouldn't necessarily. > Obviously I was wrong. Well, not quite. We shouldn't accept non-documented properties in DT, and documenting the property is certainly appreciated. The issue here seems to be an inconsistency between how we handle GPIO-backed interrupts described in DT vs ACPI. As far as I can tell from the specs I've looked at, GpioInt describes an interrupt that is backed by a GPIO. That sounds similar to what we would do in DT in that we are describing the resource logically as an interrupt. What I don't follow is why GpioInt seems to be translated as a GPIO rather than as an interrupt which happens to be backed by a GPIO. Were it not for that, the DT and ACPI cases would align better. > I'll remove the binding documentation from the next revision and call it > "ACPI only" if it makes this work for you. I would prefer not if that still leaves the property possible in the DT case. We should figure out how we cater for these differences more generally; I'm sure more are going to appear. 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