On Mon, Mar 25, 2019 at 03:12:10PM +0000, Thomas Preston wrote:
> Add an example for the magic PRP0001 device ID which allows matching
> ACPI devices against drivers using OF Device Tree compatible property.
> It wasn't clear to me that PRP0001 could be used in _CID.
Yes, but it's not necessary to have it if we have defined a _HID.
In that case PRP0001 is a temporary stub until corresponding driver
incorporates an official _HID.
On the contrary, when there is no official _HID available, PRP0001 can be used
instead directly as a _HID and no _CID is needed.
I would really recommend to look at the examples in meta-acpi repository. There
are cases like described above.
This one is good enough, though see below.
> Signed-off-by: Thomas Preston <thomas.preston@xxxxxxxxxxxxxxx>
> ---
> Documentation/acpi/enumeration.txt | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
> index 7bcf9c3d9fbe..8375fc506b47 100644
> --- a/Documentation/acpi/enumeration.txt
> +++ b/Documentation/acpi/enumeration.txt
> @@ -410,6 +410,37 @@ Specifically, the device IDs returned by _HID and preceding PRP0001 in the _CID
> return package will be checked first. Also in that case the bus type the device
> will be enumerated to depends on the device ID returned by _HID.
>
> +For example, the following ACPI sample might be used to enumerate an lm75-type
> +I2C temperature sensor and match it to the driver using the Device Tree
> +namespace link:
> +
> + Device (TMP0)
> + {
> + /* _HID will appear in sysfs */
> + Name (_HID, "PRP0001")
> +
> + /* _CID can also be used to search for "compatible" property */
> + Name (_CID, "PRP0001")
So, these lines are superfluous as stated exaxtly in a following paragraph.
> +
> + Name (_DSD, Package() {
> + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> + Package () {
> + Package (2) { "compatible", "ti,tmp75" },
> + }
> + })
> + Method (_CRS, 0, Serialized)
> + {
> + Name (SBUF, ResourceTemplate ()
> + {
> + I2cSerialBusV2 (0x48, ControllerInitiated,
> + 400000, AddressingMode7Bit,
> + "\\_SB.PCI0.I2C1", 0x00,
> + ResourceConsumer, , Exclusive,)
> + })
> + Return (SBUF)
> + }
> + }
> +
> It is valid to define device objects with a _HID returning PRP0001 and without
> the "compatible" property in the _DSD or a _CID as long as one of their
> ancestors provides a _DSD with a valid "compatible" property. Such device
--
With Best Regards,
Andy Shevchenko
