transmission of additional link layer dwords after PS_ACK

Shah, Amit M amit.m.shah at intel.com
Fri Feb 27 11:26:26 PST 2009


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Hi Gerry,
In your SAS power management proposal (08-015 rev. 7), I see something in the
power management diagram.
In the attached diagram, you show that once the PHY B transmits PS_ACK, it
would transmit few more link layer dwords and later transition to DC IDLE.
But in 08-249 r6 (proposal from Brian), the state machine will transition to
PS_QUIET state where it would request Partial or Slumber to the PHY.
So the point is, there may or may not be any link layer dwords between PM_ACK
transmission and DC IDLE. I think it is ok but as your diagram specific shows
link layer dwords after PS_ACK I want to ensure that there is no spefic
requirement here. If there is some requirement, can you throw some light on
that.
Also I think the PHY's would prefer to get some additional Dwords before DC
IDLE to ensure that PS_ACK was correctly transmitted as well correctly
received. The reason is that there is always a tendency to eat few bits
before or after DC IDLE making that DW unusable. It may be a good idea to put
a constraint of say min. "2" additional link layer dwords before DC IDLE.
Thanks,
amit
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