Allwinner A20 - Page 693

A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 693 / 812
19
R/W
R/W
0x0
per-port basis. This bit is set when Root Hub changes the
PortOverCurrentIndicator bit. The HCD writes a ‘1’ to clear this
bit. Writing a ‘0’ has no effect.
0
no change in PortOverCurrentIndicator
1
PortOverCurrentIndicator has changed
18
R/W
R/W
0x0
PortSuspendStatusChange
This bit is set when the full resume sequence has been completed.
This sequence includes the 20-s resume pulse, LS EOP, and 3-ms
resychronization delay. The HCD writes a ‘1’ to clear this bit.
Writing a ‘0’ has no effect. This bit is also cleared when
ResetStatusChange is set.
0
resume is not completed
1
resume completed
17
R/W
R/W
0x0
PortEnableStatusChange
This bit is set when hardware events cause the PortEnableStatus
bit to be cleared. Changes from HCD writes do not set this bit. The
HCD writes a ‘1’ to clear this bit. Writing a ‘0’ has no effect.
0
no change in PortEnableStatus
1
change in PortEnableStatus
16
R/W
R/W
0x0
ConnectStatusChange
This bit is set whenever a connect or disconnect event occurs. The
HCD writes a ‘1’ to clear this bit. Writing a ‘0’ has no effect. If
CurrentConnectStatus is cleared when a
SetPortReset,SetPortEnable, or SetPortSuspend write occurs,
this bit is set to force the driver to re-evaluate the connection status
since these writes should not occur if the port is disconnected.
0
no change in PortEnableStatus
1
change in PortEnableStatus
Note: If the DeviceRemovable[NDP] bit is set, this bit is set only
after a Root Hub reset to inform the system that the device is attached.
15:10
Reserved
9
R/W
R/W
-
(read)LowSpeedDeviceAttached
This bit indicates the speed of the device attached to this port.
When set, a Low Speed device is attached to this port. When clear,
a Full Speed device is attached to this port. This field is valid only
when the CurrentConnectStatus is set.
0
full speed device attached
1
low speed device attached
(write)ClearPortPower
The HCD clears the PortPowerStatus bit by writing a ‘1’ to this bit.
Writing a ‘0’ has no effect.
(read)PortPowerStatus
This bit reflects the port’s power status, regardless of the type of
power switching implemented. This bit is cleared if an overcurrent
condition is detected. HCD sets this bit by writing SetPortPower or
SetGlobalPower. HCD clears this bit by writing ClearPortPower
or ClearGlobalPower. Which power control switches are enabled