HS_USB2.0 host
RM0082
426/844
Doc ID 018672 Rev 1
[07]
LHCR
1‘h0
Light host controller reset.
This bit allows the driver to reset the EHCI host
controller without affecting the state of the ports or the
relationship to the companion OHCI host controllers.
For example, the PORSTC registers should not be
reset to their default values and the CF bit (in
CONFIGFLAG register setting should not go to zero
(retaining port ownership relationships).
If this bit is set to 1‘b0, the light host controller reset
has been completed and it is safe for host software to
re-initialize the EHCI host controller. Besides, if this
bit is set to 1‘b1, the light host controller reset has not
yet completed.
Note: If light host controller reset is not implemented,
reading this bit will always return a zero value (1‘b0).
[06]
IAAD
1‘h0
Interrupt on async advance doorbell.
This bit is used as a doorbell by software to tell the
EHCI host controller to issue an interrupt the next
time it advances asynchronous schedule. Software
must write a 1‘b1 to this bit to ring the doorbell.
When the EHCI host controller has evicted all
appropriate cached schedule state, it sets the
interrupt on async advance status bit (IAA, bit [5]) in
the USBSTS register. If the Interrupt on async
advance enable bit in the USBINTR, is set, then the
EHCI host controller will assert an interrupt at the
next interrupt threshold.
Note: The EHCI host controller clears the IAAD bit
after it has set the IAA status bit in the USBSTS
register.
Note: In order to avoid undefined results, software
should not set this bit when the asynchronous
schedule is disabled.
[05]
ASE
1‘h0
Asynchronous schedule enable.
This bit controls whether the EHCI host controller
skips processing the asynchronous schedule,
according to encoding:
1‘b0 = Don’t process the asynchronous schedule.
1‘b1 = Use the ASYNCLISTADDR register to access
the asynchronous schedule.
[04]
PSE
1‘h0
Periodic schedule enable.
This bit controls whether the EHCI host controller
skips processing the periodic schedule, according to
encoding:
1‘b0 = Don’t process the periodic schedule.
1‘b1 = Use the PERIODICLISTBASE register to
access the periodic schedule.
Table 354.
USBCMD register bit assignments (continued)
Bit
Name
Reset value Description