Table 2-11. Mixed Mode Priority Level Setting - Motorola MVME5100 Programmer's Reference Manual

Hawk PCI Host Bridge & Multi-Processor Interrupt Controller
2
HEIR
Setting
000
001
010
011
2-36
When the arbiter is programmed for round robin priority mode, the arbiter
maintains fairness and provides equal opportunity to the requestors by
rotating its grants. The contents in "HEIR" field are "don't cares" when
operated in this mode.
When the arbiter is programmed for mixed mode, the 8 requestors are
divided up into 4 groups and each groups is occupied by 2 requestors.
PARB6 and PARB5 are defined in group1; PARB4 and PARB3 are
defined in group 2; PARB2 and PARB1 are defined in group 3; PARB0
and HAWK are defined in group 4. Arbitration is set for round robin mode
between the 2 requestors within each group and set for fixed mode between
the 4 groups. The levels of priority for each group are programmable by
writing the "HEIR" field in the PCI Arbiter control register.
describes all available setting for the "HEIR" field in mixed mode.

Table 2-11. Mixed Mode Priority Level Setting

Highest
group 1 group 2
PARB6 & 5 PARB4 & 3
group 4 group 1
PARB0 & PARB6 & 5
HAWK
group 3 group 4
PARB2 & 1 PARB0 &
HAWK
group 2 group 3
PARB4 & 3 PARB2 & 1
PRIORITY Levels
group 3
PARB2 & 1
group 2
PARB4 & 3
group 1
PARB6 & 5
group 4
PARB0 &
HAWK
Computer Group Literature Center Web Site
Table 2-11
Lowest
group 4
PARB0 &
HAWK
group 3
PARB2 & 1
group 2
PARB4 & 3
group 1
PARB6 & 5