[PATCH v2 13/39] acpi: Add a binding for ACPI settings in the device tree

[Simon Glass]

Hi Andy,

On Tue, 10 Mar 2020 at 08:51, Andy Shevchenko <
andriy.shevchenko at linux.intel.com> wrote:
>
> On Sun, Mar 08, 2020 at 09:44:37PM -0600, Simon Glass wrote:
> > Devices need to report various identifiers in the ACPI tables. Rather
than
> > hard-coding these in drivers it is typically better to put them in the
> > device tree.
> >
> > Add a binding file to describe this.
>
> ...
>
> > +Device bindings are described by their own individual binding files.
> > +
> > +U-Boot provides for some optional properties which are documented
here. See
> > +also hid-over-i2c.txt which describes HID devices.
> > +
> > + - acpi,has-power-resource : (boolean) true if this device has a power
resource.
> > +    This causes a PRIC (ACPI PowerResource) to be written containing
the
>
> What is PRIC?
>
> > +    properties provided by this binding, to describe how to handle
powering the
> > +    device up and down using GPIOs
>
> > + - acpi,compatible : compatible string to report
>
> Hmm... I didn't get this. Is it ACPI _CID?

Will add a pointer to the Linux ACPI docs for this.

>
> > + - acpi,desc : Contains the string to use as the _DDN (DOS (Disk
Operating
> > +    System) Device Name)
>
> > + - acpi,hid : Contains the string to use as the HID (Hardware ID)
> > +    identifier _HID
>
> HID can be dropped to avoid confusion with below.

OK I am actually dropping the next line.

>
> > + - hid-descr-addr : HID register offset (for Human Interface Devices)
>
> > + - acpi,probed : Tells U-Boot to add 'linux,probed' to the ACPI tables
so that
> > +    Linux will not re-init the device
>
> Why? How do we know that Linux will work correctly? Again, we must not
depend
> on the OS behaviour.

The wording is incorrect, will update. This is effectively an 'optional'
device.

>
> > + - acpi,uid : _UID value for device
> > +
> > +
> > +Example
> > +-------
> > +
> > +synaptics_touchpad: synaptics-touchpad at 2c {
> > +     compatible = "hid-over-i2c";
> > +     reg = <0x2c>;
> > +     acpi,hid = "PNP0C50";
> > +     acpi,desc = "Synaptics Touchpad";
> > +     interrupts-extended = <&acpi_gpe GPIO_18_IRQ
> > +                     IRQ_TYPE_EDGE_FALLING>;
> > +     acpi,probed;
> > +     hid-descr-addr = <0x20>;
> > +};

Regards,
Simon