SCSI Card with AM53C974 Chip; Devices Are Not Detected
Support knowledgebase (hoe_AM53C974_1)
Applies to
SuSE Linux: Versions since 6.1
Kernel: Version 2.2.xx
Symptom:
The SCSI controller does not detect the connected devices (e.g. scanner, CDR).
The following article is based on "Kurt Garloff's DC390 page"
and "kwown
problems".
This page presents some solutions for the chips "AM53C974 / AM79C974" included in
the SCSI controllers listed below.
- Tekram DC390(T) PCI Fast SCSI
- DawiControl2974
- Qlogic Fast! PCI Basic
- and others ...
Although the kernel also includes another driver for AM53C974,
please use the driver tmscsim (Linux DC390/AM53C974 (tmscsim) SCSI driver)
only!
Note:
The SCSI card "Tekram DC390W/U/F" is based on the
"NCR/Sym53C825/875"-chip and is supported by the driver "ncr53c8xx".
Additional problems
The author also deals with problems concerning
- Scanners (Hang up),
- JVC XR-W2010.
In this case, please refer to the original
documentation.
Cause:
The devices are not detected due to the timeout after reset.
The SCSI2's specification is not very accurate as far as the device's reaction time
to a SCSI selection, after a bus reset, is concerned.
The specification suggests a timeout of 0,25 secs.
However, this does not apply to many devices. Some scanners and CDRs (e.g.
Yamaha CRW4416) are known for having a reaction time of ca. 3 secs. to a "TEST UNIT READY"
command.
At present, the timeout after a bus reset is set by default to 0,6 seconds in the driver.
Therefore, some devices are not detected.
Solution:
Problem analysis
Requirements:
- You must know the SCSI ID and
- be logged in as root.
The script
rescan-scsi-bus.sh produces information about your SCSI system (the way
to obtain this information manually is described in the original documentation).
This script also tries to initialize those devices with a longer reaction time.
If your device is detected after executing this script again, the problem probably
laid on your device's long reaction time.
Solution
The following method provides a quick and simple solution:
Copy the script to "/usr/sbin" and add the line
sleep 10; /usr/sbin/rescan-scsi-bus.sh
to the file "/sbin/init.d/boot.local".
You can also try to reduce the system's latency before the script
"rescan-scsi-bus.sh" is invoked by changing the value after the "sleep" call.
Other possibilities to solve this problem are also described
in the original
documentation.
Keywords: SCSI, AM53C974, AM79C974, DC390, TMSCSIM, TEKRAM, QLOGIC, YAMAHACRW4416 SCANNER, CDWRITER, CDR, NOT DETECTED, DAWICONTROL, SDB_LINKS: MYLEX_DAC960, KFR_15
Categories:
SCSI
SDB-hoe_AM53C974_1, Copyright SuSE Linux AG, Nürnberg, Germany
- Version: 07. Jan 2002
SuSE Linux AG - Last generated: 08. Jan 2002 by glazzar (sdb_gen 1.40.0)