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HIDI2C Device-Specific Method (_DSM)

  • Article

The _DSM method is defined in section 9.14.1, "_DSM (Device Specific Method)", in the ACPI 5.0 specification. This method provides for individual, device-specific data and control functions that can be called by a device driver without conflicting with other such device-specific methods.

The _DSM for a particular device or class defines a UUID (GUID) that is guaranteed not to clash with other UUIDs. For each UUID, there is a set of defined functions that the _DSM method can implement to provide data or perform control functions for the driver.

For the HIDI2C class of devices, Function 1 is defined as follows:

Arguments

  • Arg0: UUID = 3cdff6f7-4267-4555-ad05-b30a3d8938de

  • Arg1: Revision ID = 1

  • Arg2: Function index = 1

  • Arg3: None

Return

An integer containing the HidDescriptorAddress. This address is the register offset in the I2C device at which the HID descriptor(s) can be read.

Function index 0 of every _DSM is a query function that returns the set of supported function indexes, and is always required. For more information, see section 9.14.1, "_DSM (Device Specific Method)", in the ACPI 5.0 specification.