INQUIRY Data field to report transceiver type

John Lohmeyer john.lohmeyer at symbios.com
Wed Sep 9 19:15:15 PDT 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* John Lohmeyer <john.lohmeyer at symbios.com>
*
                                                 T10/98-215 r0

September 9, 1998

To:       T10 Technical Committee
From:     John Lohmeyer, LSI Logic Principal Member of T10
Subj:     INQUIRY Data field to report transceiver type

Currently SCSI has no standard way for target devices to
report their transceiver types.  This proposal would define a
byte (56) in the INQUIRY Data to permit reporting of the
device's transceiver capabilities and to report the current
transceiver mode.

There are two benefits to adopting this proposal: 1) multi-
mode devices can report all of their transceiver capabilities
and 2) it may assist domain validation in detecting expanders,
particularly those that translate between transceiver modes.

I am proposing that byte 56 be defined as protocol-specific.
For parallel, this byte would be used as documented below.
For serial interfaces, byte 56 would remain reserved.

+------+-------+-------+-------+-------+-------+-------+-------+-------+
|  Bit |   7   |   6   |   5   |   4   |   3   |   2   |   1   |   0   |
|Byte  |       |       |       |       |       |       |       |       |
+------+-------+-------+-------+-------+-------+-------+-------+-------+
| 56   |   reserved    | LVD_C | HVD_C |  SE_C |         Tmode         |
+------+---------------+-------+-------+-------+-----------------------+

An LVD_C bit of one indicates that the device is capable of
supporting low-voltage differential drivers and receivers.  An
HVD_C bit of one indicates that the device is capable of
supporting high-voltage differential drivers and receivers. An
SE_C bit of one indicates that the device is capable of
supporting single-ended drivers and receivers.  If all of
these bits are zero, the device does not support this
reporting function.

The Tmode field is defined as follows:

Tmode      Description
-------    --------------------------------------------
000b       Device does not support this field or cannot
           determine its driver/receiver type
001b       Device is in single-ended mode
010b       Device is in high-voltage differential mode
011b       Device is in low-voltage differential mode
100b-111b  Reserved

--
John Lohmeyer                  Email: john.lohmeyer at symbios.com
LSI Logic Corp.                Voice: +1-719-533-7560
4420 ArrowsWest Dr.              Fax: +1-719-533-7036
Colo Spgs, CO 80907              BBS: +1-719-533-7950

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