STP initiator ALIGN frequency problem

Hoglund, Tim thoglund at lsil.com
Tue Aug 19 07:24:35 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Hoglund, Tim" <thoglund at lsil.com>
*
Pak-

I believe #2 is a requirement for the STP/SATA bridge because it is what is
directly connected to the SATA device and is responsible for insuring SATA
link protocol compliance.  The STP initiator must also insert ALIGNs to
allow the STP/SATA bridge the ability to do it's job.

TimH

~~~~~~~~~~~~~~~~~~~~~~~
Tim.Hoglund at lsil.com
LSI Logic Corporation
Storage Std Products
719/533-7450 (Voice)
719/533-7480 (Fax)
~~~~~~~~~~~~~~~~~~~~~~~



-----Original Message-----
From: Seto, Pak-lung [mailto:pak-lung.seto at intel.com]
Sent: Thursday, August 14, 2003 1:53 PM
To: Hoglund, Tim; T10 Reflector (E-mail)
Cc: Hoglund, Tim
Subject: RE: STP initiator ALIGN frequency problem


Tim

I don't believe #2 is a requirement for STP/SATA bridge, #2 is a requirement
for initiator.

-----Original Message-----
From: Hoglund, Tim [mailto:thoglund at lsil.com]
Sent: Thursday, August 14, 2003 1:48 PM
To: T10 Reflector (E-mail)
Cc: Hoglund, Tim
Subject: STP initiator ALIGN frequency problem


* From the T10 Reflector (t10 at t10.org), posted by:
* "Hoglund, Tim" <thoglund at lsil.com>
*

We believe to have identified a fundamental issue with ALIGN insertion for
STP initiators as follows (based on our interpretation of sas-r05 section
7.3).

Requirements per SAS r05 section 7.3:
1. STP initiator to insert 2 consecutive ALIGNs or NOTIFYs within each 256
dwords plus 1 ALIGN or NOTIFY within each 2048 dwords.
2. STP/SATA bridge must insert ALIGNs in pairs to SATA device, 1 pair within
each 256 dwords.

Problem:
When rate matching is in effect (3.0Gb STP initiator connected to 1.5Gb SATA
device), insufficient ALIGNs are generated by the STP initiator to allow the
STP/SATA bridge to satisfy requirement #2 above.  The pair of ALIGNs
inserted by the STP initiator per 256 dwords need to be rate matched.

Proposed remedy:
1. Require STP initiator to insert 4 consecutive ALIGNs or NOTIFYs within
each 256 dwords plus 1 ALIGN or NOTIFY within each 2048 dwords when rate
matching (need to insert 2*N consecutive ALIGNs where N is the ratio between
the physical link rate and connection rate).  In other words, the pair of
ALIGNs inserted by the STP initiator also need to rate matched, not just the
dwords.

Regards,
TimH

~~~~~~~~~~~~~~~~~~~~~~~
Tim.Hoglund at lsil.com
LSI Logic Corporation
Storage Std Products
719/533-7450 (Voice)
719/533-7480 (Fax)
~~~~~~~~~~~~~~~~~~~~~~~


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