Specifications

7-126 System Registers
Table 7-58 ICCMTR Register Bit Definitions
Name Bit(s) Type Function
RSVD
<31:4> R0 Reserved. Read as zeros.
MBX_TIP<3:0>
<3:0> W1C, 0 Mailbox Transaction in Progress. Indicates
that the I/O port has transmitted a Mailbox
Command packet, targeting the corresponding
hose, across one of the Down Turbo Vortex
buses. When the corresponding Mailbox Status
packet is received and processed, the bit is
cleared.
An incomplete mailbox transaction (no Mailbox
Status packet returned) is detected by software
using a software timeout. Software examines
this field to determine the hose used to send the
packet down. The TLMBPR register points to the
mailbox data structure that was accessed. Soft-
ware then writes a one to clear the MBX_TIP bit
,
so that the I/O port control logic no longer ex-
pects a Mailbox Status packet to be returned.
This allows subsequent mailbox transactions to
be processed.
IMPORTANT: The MBX_TIP bits should never
be cleared by software unless the software
timeout limit has been reached.
Clearing these bits prior to the software timeout
can result in Mailbox Status packets being writ-
ten to incorrect mailbox data structures.
This field is cleared by writing a one to the bit or
by setting the appropriate HOSEn_RESET bit
in the IDPNSEn register. Note that setting
HOSEn_RESET results in the initialization of
the entire I/O subsystem attached to the hose.