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HcRhDescriptorB
This register is only rest by a power-on reset (PCIRST#). It is written during system initialization
to configure the Root Hub. These bit should not be written during normal operation.
Table 18.42 HcRhDescriptorB Register
Register: HcRhDescriptorB
Offset: 4C-4F
Bits
Reset
R/W
Description
31 - 16
0000h
R/W
PortPowerControlMask
USB Host Controller implements global-power switching. This
field is only valid if NoPowerSwitching is cleared and
PowerSwitchingMode is set (individual port switching). When
set, the port only responds to individual port power switching
commands (Set/ClearPortPower). When cleared, the port only
responds to global power switching commands
(Set/ClearGlobalPower).
0 = Global power switching
1 = Individual port switching
Port Bit relationship
16 : Reserved
17 : Port 1
18 : Port 2
...
31 : Port 15
Unimplemented ports are reserved, read/write '0'.
15 - 0
0000h
R/W
DeviceRemoveable
USB Host Controller ports default to removable devices.
0 = Device removable
1 = Device not removable
Port Bit relationship
0 : Reserved
1 : Port 1
2 : Port 2
...
15 : Port 15
Unimplemented ports are reserved, read/write '0'.
Содержание HD64465
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