Is WR_FLOW bit useless?!?

Bill Galloway BillG at breatech.com
Fri Nov 10 09:15:56 PST 2000


* From the T10 Reflector (t10 at t10.org), posted by:
* "Bill Galloway" <BillG at breatech.com>
*
Sriram,

I believe that the intention was for the target to honor the WR_FLOW bit
except for error conditions.  That is not something that is easy to write
into a spec. Who is to say what is and is not an error condition.  I agree
with you, that if the initiator can not truly count on the flow control
signal ALL of the time then it is pretty much useless and no real
information is conveyed in the WR_FLOW bit.  All that the bit says today is
that the target may toggle the flow control signal if it feels like it and
the initiator may look at it if it feels like it.  Not a very useful
situation.


Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at breatech.com

-----Original Message-----
From: Sriram Srinivasan [mailto:srirams at lsil.com]
Sent: Friday, November 10, 2000 10:49 AM
To: BillG at breatech.com
Cc: t10 at t10.org
Subject: Is WR_FLOW bit useless?!?


   If the target can ALWAYS use a phase change to signal the end of the
stream AND DT_DATA_OUT streaming is MANDATORY (according to para. 8 in
section 4.9.3.3) what purpose does the WR_FLOW bit serve in the PPR
message?

   \Sriram\
~
~ Sriram,
~
~ I was not happy with it but the agreement was that a target could end
a
~ stream by changing phase or by going bus free.
~
~
~ Bill Galloway
~ BREA Technologies, Inc.
~ P: (281) 530-3063
~ F: (281) 988-0358
~ BillG at breatech.com
~
~ -----Original Message-----
~ From: owner-t10 at t10.org [mailto:owner-t10 at t10.org]On Behalf Of Sriram
~ Srinivasan
~ Sent: Thursday, November 09, 2000 4:50 PM
~ To: t10 at t10.org
~ Subject: Streaming Clarification
~
~
~ * From the T10 Reflector (t10 at t10.org), posted by:
~ * Sriram Srinivasan <srirams at lsil.com>
~ *
~    I have a question on "how to end a read stream".
~
~    00-378r0 (SPI-4 rev1) states:
~
~    1) in the last paragraph (and NOTE-5) of section 4.9.3.3 DT_DATA_IN
~       flow control is implied by the term "read streaming"
~
~    2) in section 16.3.10.1 that RD_STRM must be negotiated to a 1 so
~       that read streaming can be used.
~
~    So putting 1) and 2) together can it be deduced that the initiator
~ will EXPECT "DT_DATA_IN flow control" (using P_CRCA) to happen during
~ read streams?  In other words:
~
~    a) Is it mandatory for the target to use the P_CRCA to end the read
~ stream?  Or
~
~    b) can it do a phase change at the end of a data stream IU and end
~ the stream (as stated in paragraph 6 of section 14.3.4 in 00-378r0)?
~
~    c) Or is the target allowed to do either a) or b) stated above?
~
~    thanx,
~    \Sriram\
~
~
~ ----------------------------------------------------------------------
~
~  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
~

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

 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
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