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I think we are in agreement. I would like to discuss the direction at the CAP meeting. From my perspective, it is not a big deal to encode the direction as a part of the opcode. However, I am a bit concerned because we could end up burning 6 opcodes for this capability (12/16 byte CDB IN/Out/Non data transfer). ------------------------------------------------ Curtis E. Stevens 20511 Lake Forest Dr. #C 214-D Lake Forest, Ca. 92630 Phone: 949-672-7933 Cell: 949-307-5050 E-Mail: [EMAIL PROTECTED] Why did the chicken cross the road? Colonel Sanders: You mean I missed one? -----Original Message----- From: Sheffield, Robert L [mailto:[EMAIL PROTECTED] Sent: Friday, October 29, 2004 8:51 AM To: [EMAIL PROTECTED] Cc: Andy Warner; Curtis Stevens Subject: RE: [t13] RE: comment on T10 ATA-passthru I'm not sure what all the fuss is about redundant transfer-direction informaiton. SCSI op-codes are partitioned so that a given op-code corresponds either to a transfer-in, or a transfer-out (bidirectional and non-transfer commands excepted). There is no SCSI opcode that sometimes does a transfer-in, and sometimes does a transfer-out, depending on other information. Nonetheless, all SCSI HBA driver interfaces provide in a "wrapper" of some sort, and indication of the direction of the data transfer, even though that information is already evident in the op-code. Why? Because the HBA doesn't want to be burdened with parsing the CDB itself. The very same concept is at play here - with respect to the embedded ATA command. Only in this case, the SCSI command itself is the "wrapper" for the embedded ATA command, and so the SCSI CDB should contain an indication of the transfer direction. Now - to be fully consistent with existing SCSI models, we recognize that the SCSI/ATA passthrough CDB has a SCSI op-code. All SCSI op-codes defined so far indicate a transfer direction as part of the opcode (if there is a transfer at all). That being the case, it might be prudent to define distinct SCSI op-codes for transfer-in ATA passthrough commands and transfer-out ATA passthrough commands. That, apart from being consistent with the definition of existing SCSI opcodes, frees up another bit in the CDB to use for some other purpose. Regards, Bob -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Andy Warner Sent: Thursday, October 28, 2004 7:39 PM To: Curtis Stevens Cc: Andy Warner; [EMAIL PROTECTED] Subject: Re: [t13] RE: comment on T10 ATA-passthru This message is from the T13 list server. Curtis Stevens wrote: > Andy > > I am considering removing UDMA entirely since no command actually > calls out UDMA as it's protocol. You won't hear a peep of complaint from me. I (linux) can't use it because I'm on the other side of the controller from any DMA/UDMA distinction. It all looks the same for me. I don't see how Linux would use Bus Idle for the same reason. Feel free to chop that if you feel the urge. I'd still like to remove the duplicate direction indications, though. Next week I plan on updating the linux version, so let me know if you publish r6 and I'll snap straight to that. Is the magic number assignment on the agenda for November's T10 meeting ? -- [EMAIL PROTECTED] Andy Warner Voice: (612) 801-8549 Fax: (208) 575-5634
