problem with external usb2 devices (ehci??)
Hi all,
I can't get my device working (reliably) at full speed (480Mbit/s).
- copying large file to external hard disk
- packet-writing data to udf-formatted dvd+rw
"hangs" the devices (device offlined, bus reset, I/O errors, and the like).
The dvd-rw is a LaCie DVDRW USB (actually a NEC DVD_RW ND-3500AG Rev: 2.07).
I assume the NEC drive is ide, and LaCie added the usb2 interface.
I read many threads in the Internet about what seems to be an "ehci kernel
issue"
- http://kerneltrap.org/node/3844
- http://www.linuxquestions.org/questions/archive/18/2004/09/4/237048
- http://www.linuxquestions.org/questions/archive/18/2004/09/4/235072
- http://bugme.osdl.org/show_bug.cgi?id=4057
....but I did not find any solution :-(
Now, both the hd and the lacie work when attached to usb1 bus (tried with a
laptop and a desktop PC, all running sid unstable with kernel>=2.6.11), and
both fail on large-file-transfer when connected to usb2 bus.
Some (I hope) usefull info about the HW.
The desktop PC, running sid/kernel 2.6.12, is based on ASUS A7V8X-X ACPI
(BIOS Revision 1008) motherboard (VIA chipset ...I read somewhere that the
southbridge may have timings problems or doesn't fully honor the usb2
specification "M$ has the workarounds...").
The laptop is an ASUS L3000E/T. It lacks usb2 so I used a PCMCIA USB2
controller (ST-LAB USB-2). The CardBus bridge is "Ricoh Co Ltd RL5c476 II
(rev a8)"
external hard disk
------------------
In order to succesfully copy large file (>2GB) using usb2 I wrote a script
that splits source file and copies "small" chunks (about 200MB each) with
dd. If I copy the same file with cp the copy fails.
This is just a workaround for console copy.
external dvd writer
-------------------
only formatting and copying of small file works.
the workaroung described above is not applicable here because the dvd drive
is being used with gui (kde) (I assume kio-slave doesn't use cp to copy
files among windows, so just linking cp to my script would be useless,
please tell me if I'm wrong).
Using 4.3Gb dvd+rw at "floppy-speed" is really unpractical :-/
Any ideas?
Thanks,
Gabriele
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