A SAS Outstanding Xfer_RDY Question.

Evans, Mark Mark_Evans at maxtor.com
Fri Jun 27 14:29:00 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Evans, Mark" <Mark_Evans at maxtor.com>
*
Hi Bob,

If the value in the FIRST BURST SIZE field is not zero, all of the rules for
first burst are the same as for an XFER_RDY, that is, a SAS target port
shall not send an XFER_RDY until all of the data for the first burst has
been sent.  This is explicit in the standard in 10.2.6.1.5 FIRST BURST SIZE
field.  The following is the fourth paragraph in that clause:

"If the amount of data to be transferred for the command is less than the
amount of data specified by the FIRST BURST SIZE field, the SSP target port
shall not transmit an XFER_RDY frame for the command.  If the amount of data
to be transferred for the command is greater than the amount of data
specified by the FIRST BURST SIZE field, the SSP target port shall transmit
an XFER_RDY frame after it has received all of the data specified by the
FIRST BURST SIZE field from the initiator.  All data for the command is not
required to be transferred during the same connection in which the command
is transferred."

I guess we could make this stronger by changing, "...the SSP target port
shall transmit an XFER_RDY frame after it has received all of the data
specified by the FIRST BURST SIZE field..." to "...the SSP target port shall
not transmit an XFER_RDY frame until it has received all of the data
specified by the FIRST BURST SIZE field...", but the first was intended to
mean the second.

Regards,

Mark Evans
Maxtor Corporation

 -----Original Message-----
From: 	Sheffield, Robert L [mailto:robert.l.sheffield at intel.com] 
Sent:	Friday, June 27, 2003 12:44 PM
To:	t10 at t10.org
Subject:	RE: A SAS Outstanding Xfer_RDY Question.

* From the T10 Reflector (t10 at t10.org), posted by:
* "Sheffield, Robert L" <robert.l.sheffield at intel.com>
*
I didn't see this the last time I looked into the question, but it does look
like only one XFER_RDY can be outstanding at a time. I looked into it before
because of a question about the first burst transfer, and what sort of
timeout might occur in case the first burst never completes. I assumed that
since the first burst is an implicit XFER_RDY, that the timeout would be the
same whether it's the first burst or a transfer associated with an explicit
XFER_RDY (the Initiator Response Timeout timer). What I'm left wondering now
is if the target must wait for the first burst transfer to complete before
sending the first XFER_RDY? Is that the intent, and is is stated anywhere?

Bob Sheffield

-----Original Message-----
From: Sriram Srinivasan [mailto:srirams at lsil.com]
Sent: Friday, June 27, 2003 11:31 AM
To: t10 at t10.org
Subject: RE: A SAS Outstanding Xfer_RDY Question.


* From the T10 Reflector (t10 at t10.org), posted by:
* Sriram Srinivasan <srirams at lsil.com>
*

  If sas-r04a.pdf is the current SAS spec, I see that in "10.2.1.8 Receive 
Data-Out transport protocol service" it talks about limiting number of 
outstanding XFER_RDY frames per command to 1.  I don't see where it allows 
more than 1 outstanding XFER_RDY frame per command.
  
  
  \Sriram\
  
" 
" * From the T10 Reflector (t10 at t10.org), posted by:
" * "Bill Galloway" <BillG at breatech.com>
" *
" I believe the current SAS spec allows more than one outstanding XFER_RDY 
per
" command.  There was some talk of limiting this but it never went anywhere.
" 
" Bill Galloway
" Pivot3, Inc.
" BillG at pivot3.com
" P: (281) 530-3063
" F: (281) 988-0398 
" 
" -----Original Message-----
" From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Whitehill,
" Cliff
" Sent: Friday, June 27, 2003 11:03 AM
" To: t10 at t10.org
" Subject: A SAS Outstanding Xfer_RDY Question.
" 
" 
" * From the T10 Reflector (t10 at t10.org), posted by:
" * "Whitehill, Cliff" <cwhitehi at lsil.com>
" *
" All,
" 
" My current understanding is that for SAS you can have only one outstanding
" Xfer_RDY per command.  Is this true? If so, where does it say this in the
" SAS specification?
" 
" Regards,
" 
" --------------------------------------------
" Clifford A. Whitehill
" Staff Systems Engineer
" LSI Logic Corp.
" 2001 Danfield Ct.
" Fort Collins, CO. 80525
" Tel: 970-206-5024
" Fax: 970-206-5244
" email: cliff.whitehill at lsil.com
" 
" *
" * 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



----------------------------------------------------------------------
	"FORGET NOT THAT THE EARTH DELIGHTS TO FEEL YOUR BARE FEET,
               AND THE WINDS LONG TO PLAY WITH YOUR HAIR"
                                          -Khalil Gibran

 Sriram Srinivasan                       Sriram.Srinivasan at lsil.com
 ASIC Design Engineer, LSI Logic,
 2001 Danfield Ct., 				Phone: 970-206-5847
 Fort Collins, CO 80525				FAX  : 970-206-5244
----------------------------------------------------------------------

*
* 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