Datasheet

Processor Integrated I/O (IIO) Configuration Registers
174 Datasheet, Volume 2
3.3.3.27 VTISOCHCTRL—Intel
®
VT-d Isoch Related Control Register
VTISOCHCTRL
Bus: 0 Device: 5 Function: 0 Offset: 188
Bit Attr
Reset
Value
Description
31:9 RV 0h Reserved
8RW-LB0b
Intel High Definition Audio traffic to use VCp channel
1 = all VCp traffic uses the Intel High Definition Audio optimizations in Intel VT-d
pagewalk request.
0 = non-Intel High Definition Audio VCp traffic uses VC0 channel for Intel VT-d
pagewalk request.
This bit should be set whenever Intel High Definition Audio traffic is sharing VCp
with non-Intel High Definition Audio rather than running on VC1 to avoid and non-
Intel High Definition Audio to Intel High Definition Audio dependencies that can
crop up when Intel High Definition Audio traffic is also on VCp.
When this bit is cleared, VC0 can block non-Intel High Definition Audio VCp traffic.
If Intel High Definition Audio traffic is running on VCp, then VCp traffic can block
Intel High Definition Audio. Therefore, VC0 can block Intel High Definition Audio
traffic.
Intel High Definition Audio traffic will always use the optimizations regardless of
the value of this bit. This bit makes it is possible to allow non-Intel High Definition
Audio VCp to also use the Intel High Definition Audio optimizations.
7:5 RW-LB 0h
L3 Dedicated Resource for ISOCH
Number of Isoch L3 entries reserved for Intel High Definition Audio and non-Intel
High Definition Audio VCp.
USB VCp would use these reserved entries only when Isoch engine is enabled and
USB VCP is set to take High priority switch path.
000 = 16 entries when Isoch engine is enabled.
001 = 1 entry
010 = 2 entries
011 = 4 entries
100 = 8 entries
101 = 16 entries
Others = Reserved
4:2 RW-LB 0h
Number of Isoch L1 entries for Intel High Definition Audio when Isoch
Intel VT-d Engine is Enabled
000 = 16 entries (when ISOCH is enabled only)
001 = 1 entry
010 = 2 entries
011 = 4 entries
100 = 8 entries
101 = 16 entries
Others = Reserved
1RV0hReserved
0RW-LB1b
Steer Intel High Definition Audio to non-Intel High Definition Audio Intel
VT-d Engine
When this bit is set, it causes Intel High Definition Audio traffic to use the Non-
Isoch Intel VT-d engine