This message is from the T13 list server.
Jeff Garzik wrote:
This message is from the T13 list server.
More generally, there is an inherent conflict between ATA queueing and
queueing that's already defined by the command set.
If we are to support ATAPI NCQ, I would think that would involve some
amount of coupling inside the device firmware between the ATA and SCSI
command responses, and behaviors.
I still don't understand what problem you are trying to describe with
SATAPI NCQ. (Oh... Maybe this can only be discussed in secret society
meetings? If so, sorry.) What is the "inherent conflict" - a PACKET
command using NCQ is no different than a R/W FPDMA command - The command
and command parameters including the tag number are sent to the device,
the device transfers data using SATA NCQ data transfer protocol. And of
course this would require new firmware in SATAPI devices. What
additional "coupling" is required beyond what is there today in an ATAPI
device?
Ultimately, SATA is just a protocol for transporting anonymous data
packets. There, no state diagrams needed...
So on a SATA interface command packets, status packets and data packets
can be sent in any order at any time by host or device? If that is so
then why is there an Annex J in ATA/ATAPI-7?
Hale
--
++ Hale Landis ++ www.ata-atapi.com ++
