Chapter 8: PCI/G-Bus Bridge
TX7901 User’s Manual (Rev. 6.30T – Nov, 2001)
8-17
Satellite. This bit should not be changed dynamically by the application, which could cause
the system to read the wrong PCI config space and disable certain operations.
8.2.12.1.1 Satellite Mode
If the PGB is operating in the “Satellite Mode”, the PCI target Interface is disabled after reset
except to Configuration Space access cycles on the PCI Bus. The PCI interface is enabled
for target operation when one of bits [1:0] in the PCI Command Register is set by a
Configuration Write.
8.2.12.1.2 Host Mode
If the PGB is operating in the “Host Mode”, the PCI target interface is disabled after reset
until it is enabled through the Application side, i.e. the G-Bus side. The PCI interface is
enabled for target operation when one of bits [1:0] in the PCI Command Register is set by
the application.
8.2.12.2 The
PCI
Arbiter
At Reset, the PCI Arbiter is parked with the ARB_GNT[0]* signal in the active state. The
Arbiter remains in this state until RESET is deasserted and a PCI request is received..
8.2.12.3
The G-Bus Interface
At Reset, all G-Bus PCI interface registers are set to initial conditions. Pending interrupt
requests are cleared. All transactions and operations in progress are cleared. Bridge
transaction processing is disabled. PCI Configuration Space and G-Bus register interface
cycles remain enabled.
8.2.13 Retry requests
The PGB performs retry requests on the PCI bus and on the G-Bus for the following
operations:
1. The Core performs PCI retries on the PCI bus compliant with the PCI 2.1 standard.
2. A G-Bus Master is retried during the “Retry Phase” of its own read operation. See
Section 8.2.2.2.
3. A G-Bus Master is retried at a read attempt during the “Retry Phase” belonging to
another G-Bus Master. See Section 10.2.2.2.
4. A G-Bus Master is retried when the G-Bus Master and a PCI Master both request a
read simultaneously. See Sections 8.2 and 8.2.2.
5. Retry to G-Bus Master read requests before completing the posted write. See
Sections 8.2.2.2
6. The PGB posts an interrupt to the G-Bus when a transaction with a G-Bus Master
sees an error on the PCI Bus. All other G-Bus to PCI transactions will be retried.
Summary of Contents for TMPR7901
Page 1: ...TX System RISC TX79 Family TMPR7901 Symmetric 2 way superscalar 64 bit CPU ...
Page 14: ...Handling Precautions ...
Page 15: ......
Page 17: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 41: ...4 Precautions and Usage Considerations 4 2 ...
Page 42: ...TX7901 User s Manual Rev 6 30T November 2001 DOCUMENT NUMBER M 99 00004 07 ...
Page 43: ......
Page 259: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 1 13 Removed ...
Page 260: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 2 ...