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729
USB Controller Module
D07:06 R/W HCFS 00b HostControllerFunctionalState
(b = binary)
00b
USBRESET (initial state)
01b
USBRESUME
10b USBOPERATIONAL
11b USBSUSPEND
A transition to USBOPERATIONAL from another state
causes SOF generation to begin 1 ms later. The host
controller driver can determine whether the host controller
has begun sending SOFs by reading the StartofFrame field
of the HcInterruptStatus register.
The host controller can change this field only when in the
USBSUSPEND state. The host controller can move from
the
USBSUSPEND state to the USBRESUME state after
detecting the resume signal from a downstream port.
The host controller enters the
USBSUSPEND state after a
software reset, whereas it enters USBRESET after a
hardware reset. A hardware reset also resets the root hub,
and asserts subsequent reset signaling to downstream
ports.
D05 R/W BLE 0b BulkListEnable
Set to enable processing of the bulk list in the next frame.
If cleared by the host controller driver, the bulk list is not
processed after the next SOF. The host controller checks
this bit whenever it determines to process this list.
When disabled, the host controller driver can modify the
list. If HcBulkCurrentED is pointing to an ED to be
removed, the host controller driver must advance the
pointer by updating HcBulkCurrentED before re-enabling
processing of the list.
D04 R/W CLE 0b ControlListEnable
Set to enable processing the control list in the next frame.
If cleared by the host controller driver, the control list is
not processed after the next SOF. The host controller must
check this bit whenever it wants to process the list.
When disabled, the host controller driver can modify the
list. If HcControlCurrentED is pointing to an ED to be
removed, the host controller driver must advance the
pointer by updating HcControlCurrentED before re-
enabling processing of the list.
Bits Access Mnemonic Reset Description
Table 424: HcControl register