Breaking a multiple type command sequence

Sriram Srinivasan srirams at lsil.com
Mon Dec 20 13:33:16 PST 1999


* From the T10 Reflector (t10 at t10.org), posted by:
* Sriram Srinivasan <srirams at propwash.co.lsil.com>
*
>Sriram,
>I believe your every wish has been fulfilled in rev 12 of SPI-3

George:

	Well not really ;) ... I looked at SPI-3 rev. 12 and the words in 
subclause 14.3.1, 3rd paragraph (in rev. 12) currently read:
	
	"After transferring all the SPI command information unit bytes the 
target shall change to a DT DATA IN phase and transmit a SPI status information 
unit with the status defined in the SCSI Architecture Model-2 standard for this 
condition"
	
	The words can be interpreted to mean that the target needs to 
immediately send back a STATUS IU.  I suggest that the words be modified as 
given below.

	"After transferring all the SPI command information unit bytes the 
target shall change to a DT DATA IN phase and, at its earliest convenience 
(possibly, but not necessarily during the same bus connection) transmit a SPI 
status information unit with the status defined in the SCSI Architecture Model-2 
standard for this condition"
	
	This way it is clear that the target can return status immediately or 
later during this connection or on a future bus connection with the same 
initiator.  This would avoid tying up the bus while the target performs a 
non-real time check in order to determine if it has to discard this command (due 
to non-availability of resources) and return, say, a BUSY or TASK SET FULL 
status.
	


Thanx,
Sriram
	

------------------------------------------------------------------------


Sriram Srinivasan,				
ASIC Design Engineer, LSI Logic,		Phone : (970) 206 5847
2001 Danfield Ct., Ft. Collins, CO 80525	FAX   : (970) 206 5244
------------------------------------------------------------------------


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