On Fri, 7 Nov 2003, Dmitri Katchalov wrote: > Greetings, > > I finally managet to get Sony DCR-TRV17E memory stick > working with usb-storage. > The solution turned out to be very simple: > > echo "Sony:Sony DSC:0" > /proc/scsi/device_info > > But I'm puzzled as to why didn't it work in the first > place despite several reports to the contrary. My guess > is it used to work in earlier kernels and then some > seemingly unrelated change broke it. > > I investigated it a little and that's what I found: > This device uses CB transport (SENSE status not reported). > This device does not support MODE_SENSE at all. > MODE_SENSE(6) fails with STALL condition. Subsequent > REQUEST-SENSE reports ILLEGAL REQUEST. SCSI layer is > able to handle this situation, the only drawback is > that write-protect status is not reported. > > Unfortunately usb-storage sets use_10_for_ms flag > by default which causes SCSI to try MODE_SENSE(10) > first. > The device responds to MODE_SENSE(10) with "babble" > (-EOVERFLOW). scsiglue sees transport error and > tries to do a soft reset (which also fails). > Note that scsiglue does not automatically send > REQUEST-SENSE in this case. > > scsiglue then gives up after several attempts and > reports the error to the upper layer. Upper layer > (SCSI) correctly realises that MODE_SENSE(10) does > not work and attempts to fallback to MODE_SENSE(6) > but before that it issues TEST_UNIT_READY. > > This time the device responds with ILLEGAL REQUEST. > Now SCSI gets totally confused and decides to give up. > > As I understand it this ILLEGAL REQUEST actually refers > to the previous MODE_SENSE(10) command because this > error condition has never been cleared properly.
You're probably right. But that's not how TEST-UNIT-READY is _supposed_ to behave. It shouldn't be reporting the status from a previous command; it should indicate the device's current status. > If I change interpret_usb_result() in transport.c > to ignore "babble" then the next REQUEST-SENSE > reports ILLEGAL REQUEST, SCSI handles that and > everything sort of works. > > Regards, > Dmitri Patrick, what do you think about implementing that change to have the response checker retry when it gets ILLEGAL REQUEST from a TEST-UNIT-READY? Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
