Service_USB 7 - Sub host controller driver has been started. — Used for communications between USB Host Controller drivers. Shows that a sub host controller driver has been started.
| R0 | 7 (reason code) | ||||
| R1 | &80C00 (USB Service call) | ||||
| R2 | Pointer to a list of sub driver properties, used as a unique tag. | ||||
| R3 |
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Some Host controller drivers are split into two parts a generic device type handler and a specific hardware dependent support module. This allows one host controller type to have numerous differing hardware implementations without needless duplication of code.
This Service call informs the main host driver that a sub driver of its class has been started and passes a table of properties describing the sub driver. Properties are host controller driver class specific. If service call is not claimed the host class driver class supported by the sub module is either not running or has an error.