Re: [PATCH] gpiolib: acpi: use the fwnode in acpi_gpiochip_find()

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On Fri, Mar 10, 2023 at 12:42 PM Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> On Thu, Mar 09, 2023 at 02:40:51PM +0100, Benjamin Tissoires wrote:
> > While trying to set up an SSDT override for a USB-2-I2C chip [0],
> > I realized that the function acpi_gpiochip_find() was using the parent
> > of the gpio_chip to do the ACPI matching.
> >
> > This works fine on my icelake laptop because AFAICT, the DSDT presents
> > the PCI device INT3455 as the "Device (GPI0)", but is in fact handled
> > by the pinctrl driver in Linux.
> > The pinctrl driver then creates a gpio_chip device. This means that the
> > gc->parent device in that case is the GPI0 device from ACPI and everything
> > works.
> >
> > However, in the hid-cp2112 case, the parent is the USB device, and the
> > gpio_chip is directly under that USB device. Which means that in this case
> > gc->parent points at the USB device, and so we can not do an ACPI match
> > towards the GPIO device.
> >
> > I think it is safe to resolve the ACPI matching through the fwnode
> > because when we call gpiochip_add_data(), the first thing it does is
> > setting a proper gc->fwnode: if it is not there, it borrows the fwnode
> > of the parent.
> >
> > So in my icelake case, gc->fwnode is the one from the parent, meaning
> > that the ACPI handle we will get is the one from the GPI0 in the DSDT
> > (the pincrtl one). And in the hid-cp2112 case, we get the actual
> > fwnode from the gpiochip we created in the HID device, making it working.
> >
> > Link: [0]
> > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Thanks to both of you for the reviews.

Andy, should I resend a v2 with the rev-by from Mika and the Ice Lake changes?


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