On Fri, 6 Feb 2004, Joerg Schilling wrote: > >Who says it's wrong to retrieve sense information when there is an > >underrun but not Check Condition? Can you provide a reference to a > >published (or draft) document that states this? > > The SCSI standard says that the sense data should retrieved when the > CHECK CONDITION bit is set. ATAPI drives use a bit in the ATA Status > for this purpose. > > Read the SCSI CAM standard to see more on this topic.
I have checked the standards. They say that under certain circumstances the driver must perform auto-sense. As far as I can see they don't mention any circumstances under which the driver _must not_ auto-sense. > >Bear in mind that there are some transports which do not provide any > >status at all. The _only_ way for a driver to determine whether an > >error occurred is to get the sense data. > > Let us asume such transport does not exist, unless you name at least a > single transport that has no bit that means "CHECK CONDITION". The USB Control-Bulk transport does not include a status phase. This transport isn't used with CDs or DVDs; it's pretty much confined to USB floppy disk drives and digital cameras. > If you retrive sense data without reason, you may "read away" a senseful > error status that is related to a different command. That's a good point. Although for USB it's not so important, since there can only be one command running at a time. I'd like to hear what Matt Dharm and the people on the SCSI development mailing list have to say about that. Alan Stern ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
