
192
Registers
Chapter 4
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
EIDE Power Management Register
DevB:1x54
This register controls the power state of the two IDE ports. When an IDE port is powered up, it is
designed to be fully operational. When it is powered down, outputs DADDR[S,P][2:0],
DCS1[S,P]_L, DCS3[S,P]_L, DDACK[S,P]_L, DIO[R,W][S,P]_L and DRST[S,P]_L are forced
Low; DDATA[S,P][15:0], DDRQ[S,P], and DRDY[S,P] are ignored and in high-impedance mode.
When transitioning into the power-down state, DRST[S,P]_L assertion leads control over the rest of
the signals by about 1 microsecond. When transitioning into the power-up state, DRST[S,P]_L
deassertion lags control over the rest of the signals by about 1 microsecond.
Note:
Writes to [S,P]PWRDN cause [S,P]PWRX to be set High until the power state transition is
complete; while [S,P]PWRX is High, writes to [S,P]PWRDN are ignored.
Default:
00h.
Attribute:
Seebelow.
Read-Write Register
DevB:1x58
Default:
0000h.
Attribute:
Read-write.
Bits
7:6
5
Description
Reserved.
SPWRX. Power state transition for secondary IDE port.
Read-only. 1=The secondary IDE port is
transitioning from either the power-down state to the power up state (if SPWRDN = 0) or from the
power-up state to the power-down state (if SPWRDN = 1).
SPWRDN. Power down secondary IDE port.
Writing a 1 to this
fi
eld causes the hardware to
transition the secondary port from the powered-up state to the powered-down state. Writing a 0 to this
fi
eld causes the hardware to transition the secondary port from the powered-down state to the
powered-up state. When read, this bit re
fl
ects the last state written to it; however, it cannot be altered
when SPWRX is High.
Reserved.
PPWRX. Power state transition for primary IDE port.
Read-only. 1=The primary IDE port is
transitioning from either the power-down state to the power up state (if PPWRDN = 0) or from the
power-up state to the power-down state (if PPWRDN = 1).
PPWRDN. Power down primary IDE port.
Writing a 1 to this
fi
eld causes the hardware to transition
the primary port from the powered-up state to the powered-down state. Writing a 0 to this
fi
eld causes
the hardware to transition the primary port from the powered-down state to the powered-up state.
When read, this bit re
fl
ects the last state written to it; however, it cannot be altered when PPWRX is
High.
4
3:2
1
0
Bits
15:0
Description
RW.
Read-write. These bits are read-write accessible through software; they control no hardware.