Cirrus Logic EP93xx - Manual (Page 468)

11-28 DS785UM1
Copyright 2007 Cirrus Logic
Universal Serial Bus Host Controller
EP93xx User’s Guide
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HcRhDescriptorA
Address:
0x8002_0048
Default:
0x0200_1203
Definition:
Describes the root hub.
Bit Descriptions:
RSVD: Reserved. Unknown During Read.
NDP: 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 by OpenHCI
is 15.
0x03 = 3 downstream ports.
PSM: 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, the port is controlled only by the global
power switch (Set/ClearGlobalPower).
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
P RSVD
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD NOCP OCPM DT NPS PSM NDP