* Sarah Sharp | 2011-12-09 11:15:02 [-0800]: >That would be a question for Matthew. I think I remember seeing that >the full number of streams possible was one less than it needed to be >(with the abort task patch), but I didn't get around to asking him why. > >> On HS we can only send one command at a time as we have only one stream, >> right? But qdepth is set to 256 which makes you here allocate 256 >> anchors for only one command at a time. > >As Alan said, we submit multiple commands at once, and the USB 2.0 >device will let us know through the status URB which command it wants to >process first. The status URB buffers are all the same size, so we >queue one buffer for each command we submit. When we get a status URB >back, we may be getting a status for a command that isn't the same as >the cmndinfo that is housing the URB status pointer. Yeah, I just learned that after reading the spec once again. >That's why we can't rely on the context in uas_stat_cmplt, we have to >look the command up by tag. And if the device gives us the wrong tag, >what do we do in that case? Resubmit the status URB to make sure the >number of status URBs and pending commands balance out? We certainly >don't know which of the tagged commands the bad tag was for, so we don't >know which command to cancel. Probably we should just make the SCSI >core reset the device. True. > >Sarah Sharp Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
