From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Tue, 10 Mar 2020 16:50:34 +0200
Subject: [PATCH v2 13/39] acpi: Add a binding for ACPI settings in the
 device tree
In-Reply-To: <20200308214442.v2.13.I7842b2dd0d6b475301fc044c6640d8089873053f@changeid>
References: <20200309034504.149659-1-sjg@chromium.org>
 <20200308214442.v2.13.I7842b2dd0d6b475301fc044c6640d8089873053f@changeid>
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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?

> + - 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.

> + - 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.

> + - 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>;
> +};

-- 
With Best Regards,
Andy Shevchenko