Allwinner A20 - Page 690

A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 690 / 812
a powered-on port of the Root Hub. It is implementation-specific.
The unit of time is 2 ms. The duration is calculated as POTPGT *
2ms.
23:13
Reserved
12
R/W
R
0x01
NoOverCurrentProtection
This bit describes how the overcurrent status for the Root Hub
ports are reported. When this bit is cleared, the
OverCurrentProtectionMode field specifies global or per-port
reporting.
0
Over-current status is reported collectively for all
downstream ports.
1
No overcurrent protection supported.
11
R/W
R
0x0
OverCurrentProtectionMode
This bit describes how the overcurrent status for the Root Hub
ports are reported. At reset, these fields should reflect the same
mode as PowerSwitchingMode. This field is valid only if the
NoOverCurrentProtection field is cleared.
0
Over-current status is reported collectively for all
downstream ports.
1
Over-current status is reported on per-port basis.
10
R
R
0x0
Device Type
This bit specifies that the Root Hub is not a compound device. The
Root Hub is not permitted to be a compound device. This field
should always read/write 0.
9
R/W
R
0x01
PowerSwitchingMode
This bit is used to specify how the power switching of the Root Hub
ports is controlled. It is implementation-specific. This field is only
valid if the NoPowerSwitching field is cleared.
0
All ports are powered at the same time.
1
Each port is powered individually. This mode allows port
power to be controlled by either the global switch or
per-port
switching. If the PortPowerControlMask bit is set, the
port responds only to port power commands
(Set/ClearPortPower). If the port mask is cleared, then
the port is controlled only by the global power switch
(Set/ClearGlobalPower).
8
R/W
R
0x0
NoPowerSwithcing
These bits are used to specify whether power switching is
supported or ports are always powered. It is
implementation-specific. When this bit is cleared, the
PowerSwitchingMode specifies global or per-port switching.
0
Ports are power switched.
1
Ports are always powered on when the HC is powered
on.
7:0
R
R
0x01
NumberDownstreamPorts
These bits specify the number of downstream ports supported by
the Root Hub. It is implementation-specific. The minimum number
of ports is 1. The maximum number of ports supported.