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STP2002QFP
Sun Microelectronics
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
ERRATA 99.1 Description of Errata in FEPS Rev 2.2
The following are some known problems and workarounds for Rev 2.2. of the
FEPS. The device driver for the SCSI channel has software workarounds for
all of these problems.
9.1.1 SCSI DVMA/Channel Engine (CE)
9.1.1.1 SCSI CE Byte Count Gets Frozen
During SCSI write, under a set of conditions, 1 byte could get stuck in the
SCSI CE. The symptom, root cause, and workaround are described in detail
below.
Symptom:
This problem shows up only under the following conditions.
• SCSI write, and
• Starting address is an odd number,and
• Byte count is an odd number,and
• The combination of starting address and byte count should be such that
the transfer ends on a burst boundary,and
• D_BCNT stops decrementing (which can happen under the following
condition)
Condition #1: If D_BCNT is read after the DMA has been started.
If all of the above conditions are satisfied, the SCSI CE does not write the
last one byte to the FAS366. So the FAS366 is waiting in the DOUT phase
with a byte count of 1. So, for the problem to occur, all of the above condi-
tions have to be met, that is problem = a & b & c & d & e;
Root Cause:
Under the condition described above, the D_BCNT stops decrementing.
Since only two bytes can be written to the FAS366 at one time, the last one
byte has to be padded with another byte before it can be written to the
FAS366. For the logic which does the padding and writing to the FAS366, the