AMD SB600 User Manual
Page 276
©2008 Advanced Micro Devices, Inc.
Host PCI Bridge Registers (Device 20, Function 4)
AMD SB600 Register Reference Manual
Proprietary
Page 276
Misc Control Register - 32 bits - [PCI_Reg: 64h]
Field Name
Bits
Default
Description
Prefetch Enable For
Upstream Read Line
and Read Multiple
7
1h
0: Prefetch is disabled for upstream memory read line and
memory read multiple.
1: Prefetch is enabled for upstream memory read line and
memory read multiple.
Also refer to reg0x40[4] and reg0x64[21].
PCI5 Enable
8
0h
Setting this bit will enable PCIGNT5#/PCIREQ5# and
PCICLK7.
Note: These three pins are all using this single configuration
bit to enable them into PCI functionality. Care should
therefore be taken to ensure that they are used as intended.
Since PCICLK7 is not programmed as PCICLK by default,
the BIOS needs exercise a certain sequence in order to
make the clock valid. For more information consult the
AMD
SB600 Register Programming Requirements
guide
.
Arbiter 2 Enable
9
0h
Enables the use of the new PCI bus arbiter to replace the
old arbiter.
Hold Current Grant
10
0h
When set, PCIGNT# will not be deasserted until the
requesting agent deasserts its PCIREQ#. This only applies
to the new PCI bus arbiter
Single Cycle Prefetch
Control
11
1h
If a prefetch read cycle comes from SPCI bus, prefetching
may not be necessary if the cycle is single data phase. PCIB
can optionally treat the single cycle as non-prefetch and only
asks for one dword from AB.
1—Turn on the ability to treat single data phase cycle as
non-prefetch cycle.
0—Turn off the ability to treat single data phase cycle as
non-prefetch cycle.
Fast Grant Deassert En
12
0b
This control bit applies only to the old (default) PCI arbiter.
Normally PCIGNT# is deasserted two clocks after PCIREQ#
deasserts. With this bit set, PCIGNT# will deassert 1 clock
after PCIREQ# deasserts. Recommendation is to have this
bit set.
Reserved 20:13
0h
Prefetch Disable for
Upstream Mem Read
21
0h
In A11~A13: Reserved.
In A21 and later versions:
0: Prefetch is enabled for upstream normal memory read
(other than read line or read multiple). However, if
reg0x64[7]=0, then this prefetch is still disabled.
1: Prefetch is disabled for upstream normal memory read
(other than read line or read multiple).
Also refer to reg0x40[4] and reg0x64[7].
Reserved 31:22
0h