SAS-2: Notify Power Loss

George Penokie gop at us.ibm.com
Tue Oct 24 10:58:51 PDT 2006


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Steve,
Yes, I am aware of that as Mark pointed it out to me last week. He sent me 
a note with some suggestions on how it should be handled. I plan on 
putting a fix into my 06-451 proposal.
Bye for now,
George Penokie
Dept 9A8 030-3 A410
E-Mail:    gop at us.ibm.com
Internal:  553-5208
External: 507-253-5208
Stephen FINCH <steve.finch at st.com> 
10/24/2006 11:18 AM
To
"T10 Reflector" <t10 at t10.org>, George Penokie/Rochester/IBM at IBMUS
cc
Subject
SAS-2:	Notify Power Loss
Section 7.2.5.10.3 states:
"If a SAS target device supports NOTIFY (POWER LOSS EXPECTED) and receives 
NOTIFY (POWER LOSS
EXPECTED) on an SSP target port, then each SAS phy within the target 
device shall:
a) if there is an SSP connection, then transmit a BREAK on that 
connection; and
b) respond to SSP connection requests with OPEN_REJECT (RETRY) until the 
power loss timeout
timer expires or power is lost.
If any frames are received by the SAS target device after receiving NOTIFY 
(POWER LOSS EXPECTED)
before a connection is closed, then the SAS target device shall discard 
the received frames."
Since it is the CC state machine that transmits BREAK primitives, I looked 
to that state machine to see where and how this is accomplished. 
There is no inputs to that state machine indicating the reception of a 
NOTIFY (POWER LOSS EXPECTED).
That being the case, I thought maybe the SSP state machine had an input 
for the NOTIFY (POWER LOSS EXPECTED) and, in turn, would issue a Request 
Break to the CC state machine.
SURPRISE! SURPRISE!
The SSP state machine doesn't have such an input either.  And there is no 
input to the SSP state machine from higher levels that can generate a 
BREAK.
SO, how are NOTIFY (POWER LOSS EXPECTED) supposed to be handled?
I think we need state machine changes in the Link Layer to handle the 
requirements above, or we need to remove the requirements.
Regards,
Steve Finch
STMicroelectronics
303 381-3587



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