User`s guide

DWMBB Adapter
3.14.5 XMI Lockout Testing
The DWMBB uses a software programmable limit of failed IREAD
attempts before the XMI LOCKOUT L signal is asserted. Lockout Limit
(AUTLR<31:28>), when set to zero, causes the DWMBB to assert the XMI
LOCKOUT L signal after the first failed IREAD attempt.
Table 3–22 lists the bits in ADG1 used to test the four lockout modes. It is
necessary to clear ADG1<10> before clearing ADG1<30>.
Table 3–22 Lockout Diagnostic Bits
Name Location Description
Receive Lockout Status ADG1<30> Sets when the XMI LOCKOUT L signal asserts. Used with
Lockout Response Enable (ACSR<5>) to test the DWMBB’s
response to the assertion of lockout by another node.
Transmit Lockout Status ADG1<29> Sets when the DWMBB asserts the XMI LOCKOUT L signal.
Used with Lockout Assert Enable (ACSR<4>) to test the
DWMBB’s assertion of lockout after the lockout limit is exceeded.
Force Transmit Lockout ADG1<10> Forces the DWMBB to assert the XMI LOCKOUT L signal and
a loopback of the signal back into the DWMBB. This allows
diagnostic software to test the DWMBB’s response to the
assertion of the XMI LOCKOUT L signal.
3.14.6 Timeout Testing
Section 3.8 describes the programmable timeout feature of the DWMBB.
Retry timeout can be tested by reducing the timeout limit value to the
smallest time, 64 s, and attempting an access of nonexistent memory.
3.14.7 Control Reset
It is possible to do a reset without losing status information. When
Control Reset (ACSR<30>) is set, a partial node reset is initiated, allowing
the DWMBB/A module’s CSRs and PMRs to remain unchanged while the
control logic in the DWMBB/A module gate array and the DWMBB/B
module reinitialize to their power-up state. The DWMBB/A module CSRs
can then be read to determine the cause of an error.
If Control Reset is set while the DWMBB is performing DMA transactions
and a DMA transaction is interrupted as it is about to be issued or is being
issued on the XMI, the results are undefined.
If the DWMBB detects a write from the XMI to the ACSR with Control
Reset set, it executes the command even if it is currently busy or "hung."
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