On Thu, 27 Nov 2003, Kleiner Hampel wrote: > Alan Stern wrote: > > You will have to manually edit the file drivers/usb/storage/scsiglue.c in > > your kernel source. Around about line 320 in the file you may or may not > > see a line that says > > > > .max_sectors = 240, > > > > If it's there, try changing the 240 to 120. If it's not there, try adding > > This works! > I changed the value from 240 to 120. All other values between these two > points don't work - why?
I'm glad to hear you got it working. Are you sure that _all_ values don't work? I would expect that at least 128 would be okay. But no, I can't explain what's going on with your device. > Does this mean now, my usb 2.0 storage wouldn't act as "normal" usb 2.0 > speed? Or does this only mean more work for kernel? This isn't diretly connected with the speed; it's more a question of how much data can be sent in a single command. Setting max_sectors to 120 limits the driver to sending 60 KB at once (a sector is 512 bytes). That's not a problem -- all the data will be sent -- it just has to be broken up into more commands. So there's extra overhead and extra work because of the extra commands, which will slow things down a bit. Probably not too much though. Anyway, it's better than not working at all! It's a little odd that your device can only accept such a small amount of data at a time. Almost all USB storage devices can handle up to 120 KB (that's why the default value of max_sectors is 240) and most can handle arbitrarily large amounts. In the future I expect there will be a way to set the max_sectors value directly, without having to change the kernel source. In the meantime, you'll just have to make the change by hand. > Many thanks for your good help A. Stern! > > regards, > hampel You're welcome. 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
