On Mon, Dec 09, 2002 at 06:11:32PM -0800, Matthew Dharm wrote: > On Mon, Dec 09, 2002 at 05:34:11PM -0800, Greg KH wrote: > > On Mon, Dec 09, 2002 at 05:32:02PM -0800, David Brownell wrote: > > > >>... > > > >>Dec 9 15:22:26 soap kernel: usb-storage: > > > >>usb_stor_bulk_transfer_sglist(): xfer 65536 bytes, 16 entries > > > >>Dec 9 15:22:26 soap kernel: usb-storage: Status code -121; transferred > > > >>65037/65536 > > > >>Dec 9 15:22:26 soap kernel: usb-storage: -- unknown error > > > > > > That's not a timeout, "-EREMOTEIO" means it got a short read. > > > In this case, that last packet included only 13 bytes not 512. > > > (Assuming this was at high speed, otherwise it wasn't the last > > > one, and that was likely 13 bytes out of 64.) > > > > Yeah, that suggests that either usb-storage needs to handle this > > somehow, right? > > No. That's a bogus thing for a drive to do. It _should_ just NAK when > there is no data until data becomes available. > > A short packet indicates the end of the data phase.
So the device is buggy when pushed as fast as we now are? > > > Given there's only one place in the EHCI driver where EREMOTEIO > > > shows up, I'm tempted to believe that the hardware really did > > > return a short read in that last packet. > > > > > > As for why it did so, no ideas just now. Though I wonder if > > > maybe retrying short reads wouldn't help, on the premise that > > > the disk had a temporary "can't keep up" problem, since using > > > those scatterlist operations drives that hardware much faster > > > than it was ever driven by earlier kernels. > > Ack! No! No retrying short reads. We need to be able to see them! > > > But does that deserve the long "reset the endpoint" delay that happens > > because of this? I'd rather have a bit slower throughput and no long > > delays, than shorter bursts of data, with long delays, cutting the end > > throughput way down. > > Well, the reset logic is slow because some devices need that much time. > You shouldn't be resetting, because you shouldn't be getting short reads. > We need to fix the root cause, not the symptoms. I agree, any ideas? greg k-h ------------------------------------------------------- This sf.net email is sponsored by: With Great Power, Comes Great Responsibility Learn to use your power at OSDN's High Performance Computing Channel http://hpc.devchannel.org/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
