VT8601 Via, VT8601 Datasheet - Page 142

• Manufacturer Part Number: VT8601
• Description: Slot-1 / Socket-370 PCI North Bridge
• Manufacturer: Via

Graphics Controller Power Management
The ProMedia Graphics Controller power mangement feature
set complies with AGP and PCI power management
requirements.
Power Management States
Power management states (D0-D3) for both ACPI and PCI
Bus Power Management (PCI PM) refer to the same states
described in the Device Class PM Reference Specification for
Display Devices, which are equivalent to the VESA™ DPMS
power states. System software should access the ProMedia’s
configuration registers to perform PCI PM state transitions.
Power Management Clock Control
If the system “South Bridge” sends a request to the ProMedia
to power down the memory controller, the ProMedia first uses
CLKRUN# (the same signal appearing external to the
ProMedia) to check to see if the internal graphics controller
needs to access main memory. The graphics controller logic
will detect CLKRUN# high for 2 or 3 PCICLK’s and check if
there are any:
If either condition exists, the graphics controller logic will
assert CLKRUN# low for 2 PCICLK’s to signal the clock
generator to keep PCICLK running.
PME# is not implemented since there are no wake-up
conditions.
Revision 1.3 September 8, 1999
PCI PM
State 0
State 1
State 2
State 3
State
(D0)
(D1)
(D2)
(D3)
7HFKQRORJLHV ,QF
Table 12. PCI Power Management States
Internal buffers not emptied
PCI Master or AGP Master actions pending
:H &
:H &R R QQHFW
(H/Vsync Both Off)
QQHFW
DPMS State 0
DPMS State 1
DPMS State 2
DPMS State 3
(Hsync Off)
(Vsync Off)
Graphics
Fully On
Suspend
Desktop
Standby
Off
(MCLK/VCLK Both Off)
Proprietary State 0
Proprietary State 1
Proprietary State 2
Same as State 2
(VCLK Off)
Notebook
Graphics
Fully On
Standby
Suspend
-136-
Power Management Registers
Power management control for the ProMedia Graphics
Controller is provided by extended registers SR24 (Power
Management Control), GR20 (Standby Timer Control), GR21
(Power Management Control 1), GR22 (Power Management
Control 2), GR23 (Power Status), GR24 (Soft Power Control),
GR25 (Power Control Select), GR26 (DPMS Control), GR27-
28 (GPIO Control), GR2A (Suspend Pin Timer), GR2C
(Miscellaneous Pin Control), GR2F (Miscellaneous Internal
Control), and Graphics Controller PCI Configuration Indices
90-97 (PCI Power Management Registers 1 and 2).
VT8601 Apollo ProMedia
Functional Descriptions