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 <[email protected]> > --- > 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
