SAS SSP Link Layer

Day, Brian bday at lsil.com
Tue Oct 22 12:17:06 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* "Day, Brian" <bday at lsil.com>
*
I see that this was discussed on the conf call today.  There wasn't 
an answer to #2, and Bill Galloway was going to look into it.

Just very recently, Vetri and I went through this.  We believe the answer to
#2 is that you need to know the arguments because there does need to be
different behaviour depending on whether there was an ACK/NAK timeout.

You only want to reinitialize the DONE timeout timer for the cases of
Close Connection argument or Credit Timeout argument, because in those cases

the other device is still allowed to transmit frames (if there is credit) 
indefinately.  

However, any other case (currently only ACK/NAK Timeout), the
other device must issue the DONE within 1 ms.  After 1 ms, the "ACK/NAK
Timeout device" needs issue
a BREAK, regardless of whether there are more frames to send.  It is using
the DONE timeout timer for
this timeout too from what I could tell.

Brian Day
LSI Logic

-----Original Message-----
From: Ayyavu, Vetrivel [mailto:vetri at lsil.com]
Sent: Monday, October 07, 2002 1:16 PM
To: 't10 at t10.org'
Subject: SAS SSP Link Layer


* From the T10 Reflector (t10 at t10.org), posted by:
* "Ayyavu, Vetrivel" <vetri at lsil.com>
*
Hi,
       I have questions about the section 7.16.7.6 SSP_D1:DONE_Wait state
description (Page 171 in Revision 2 - 23September 2002 spec).

This is the paragraph..........

"If the DONE Received parameter has not been received from the
SSP_R1:Receive state when the Wait For DONE Parameter is received from the
SSP_TF4:Indicate_DONE_Tx state, this state shall initialize the DONE timeout
timer to 1ms. If the Wait For DONE parameter was received with the Close
Connection argument or the Credit Timeout argument, the DONE timeout timer
shall be re-initialized to 1ms each time the EOF Received parameter is
received from the SSP_R1:Receive state"

The questions are.....

1. Why ACK/NAK Timeout has not been included as an argument to re-initialize
the DONE timer? is it typo?.
2. Why do we need the arguments (Close Connection or Credit Timeout or
ACK/NAK Timeout etc) from the SSP_TF4: Indicate_DONE_Tx state?  What if we
re-initialize the DONE timer without knowing the arguments? (ie."If the Wait
For DONE parameter was received, the DONE timeout timer shall be
re-initialized to 1ms each time the EOF Received parameter is received from
the SSP_R1:Receive state").

As I understood, this state requests SL state to transmit either CLOSE or
BREAK. 
If the DONE Received parameter is received       ---> Sends CLOSE
If the DONE Received parameter is not received and DONE Timeout ---> Sends
BREAK



thanks,
Vetrivel Ayyavu
LSI Logic
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