USB Mass storage sub-class for MMC devices

Curtis Stevens curtis.stevens at wdc.com
Thu Sep 20 17:56:27 PDT 2007


* From the T10 Reflector (t10 at t10.org), posted by:
* "Curtis Stevens" <curtis.stevens at wdc.com>
*
Today in T10 we had several standards up for renewal and chose to renew some
of them simply because there are devices that still do whatever...
Devices are definitely still using subclass 02 and things are working fine.
That is the message I have received so far.  Bill sent out his E-Mail asking
for more feedback.  All I am saying is that the MSC Overview has not been
updated since MMC-2 was published.  Originally, subclass 02 was assigned to
SFF-8020, the MMC reference was added during a later revision.	This
activity happened after the introduction of subclass 06.  The update kept
subclass 02 consistent with the standards and documents of the time.  This
would be a normal and evolutionary update in line with practices that are
already present in the industry.
So, in short, I do not believe that this is redefining anything.  Nor is
this going to affect anyone's implementation.  However, if device
manufacturers continue to ship subclass 02, then obsoleting subclass it will
have the effect of moving the MSC Overview out of synch with normal industry
practice just a little further.  The is no incentive for someone to change
what they are currently doing and I do not believe that obsoleting the
subclass will cause this to disappear from anyone's host driver.
The only value proposition there is in marking something obsolete is that
you do not have to maintain the feature in the specification as new features
are added.  In this case, the capability is in use and has very little in
the way of maintenance needs.  If you change "MMC-2" to "MMC-2 and later",
then there should be no maintenance needed as the doc moves forward.
 
 
-------------------------------------------------
Curtis E. Stevens
20511 Lake Forest Drive #C-214D
Lake Forest, California 92630
Phone: 949-672-7933
Cell: 949-307-5050
E-Mail: Curtis.Stevens at WDC.com
-----Original Message-----
From: jgeldman at lexar.com [mailto:jgeldman at lexar.com] 
Sent: Thursday, September 20, 2007 5:24 PM
To: Curtis Stevens; billmc37 at ctesc.net; t10 at t10.org; mtfuji5 at avc-pioneer.com
Subject: RE: USB Mass storage sub-class for MMC devices
This is a valid alternative. However, if you favor it, I would like to
understand why. 
As Katata-san suggested in the meeting, OS's are likely to continue to
support devices they already support.
Is there perphaps some advantage in having devices & OS's continue to
declare identical functionality in two mass storage subclasses?  
Thanks, 
John Geldman
Lexar Media
47300 Bayside Parkway
Fremont, CA 94538
P: 510 580-8715
C: 510 449-3597
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Curtis
Stevens
Sent: Thursday, September 20, 2007 4:16 PM
To: Bill McFerrin; t10 at t10.org; Mt.Fuji
Subject: RE: USB Mass storage sub-class for MMC devices
* From the T10 Reflector (t10 at t10.org), posted by:
* "Curtis Stevens" <curtis.stevens at wdc.com>
*
An alternative would be to change subclass 02h to say MMC-2 and above...
 
 
-------------------------------------------------
Curtis E. Stevens
20511 Lake Forest Drive #C-214D
Lake Forest, California 92630
Phone: 949-672-7933
Cell: 949-307-5050
E-Mail: Curtis.Stevens at WDC.com
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Bill
McFerrin
Sent: Thursday, September 20, 2007 2:15 PM
To: t10 at t10.org; Mt.Fuji
Subject: USB Mass storage sub-class for MMC devices
* From the T10 Reflector (t10 at t10.org), posted by:
* Bill McFerrin <billmc37 at ctesc.net>
*
Members:
Curtis Stevens (Western Digital) came to our MMC WG meeting on 19 September
2007 to bring up a concern about UBC mass storage bridge implementations.
The drive sub-class may be specified as either
SFF8020/MMC-2 (value = 2) or Transparent SCSI (value=6). Since SFF8020 is
obsolete and MMC-2 has been withdrawn as a standard, we should act to
promote the use of only drive sub-type 6. Keiji Katata (Pioneer) proposed
that drive sub-type 2 be made obsolete. If you are aware of common use of
drive sub-type 2, please respond to this message.
Kind Regards,
Bill McFerrin
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org



More information about the T10 mailing list