I did a small Linux-USB plugtest on my machine
with around 25 USB devices. Here are the config and
results.
Pentium III 500 MHz + PIIX4 UHCI + add-in PCI/OHCI
USB Devices (25 with hubs):
on root hub A: 4-port ADS external self-powered hub
. cpia camera
. Philips speakers
. Y-E DATA floppy drive (old/black)
. Cherry hub/keyboard (bus-powered)
. Key/Genius mouse
. Logitech mouse
. Compaq modem
. Entrega hub4U (self-powered)
. Logitech webcam (no driver)
. Logitech mouse
. Intel ProShare camera (no driver)
. Y-D DATA floppy drive (new/gray)
on root hub B: 7-port Ark (FTDI) external self-powered hub
. BTC keyboard
. Qtronix keyboard
. prototype keyboard #1
. Aspire keyboard/hub/HID(controls)
. USB Zip-100 drive
. Microsoft Natural Elite keyboard
. prototype keyboard #2
. Logitech mouse
a. using usb-uhci.o:
~~~~~~~~~~~~~~~~~~~~~~~~~~~
All keyboards and mice work.
All 3 usb-storage drives are found and listed in
/proc/scsi/scsi.
"cat /proc/bus/usb/devices" sometimes produces
"usb-uhci.c: interrupt, status 2, frame# NNN" messages.
It also says "(truncated)" at the end of the
nearly 8 KB output because the /proc strings from all
of these devices overflows the 8 KB allocated space.
After modifying devices.c to use 16 KB for its proc
output, there is no "(truncated)" message and the
output is around 13 KB.
Unloaded all modules OK.
b. using uhci.o:
~~~~~~~~~~~~~~~~~~~~~~~
6 of 7 keyboards are working.
All 4 mice work.
All 3 usb-storage drives are found.
All 3 are listed as diretories in /proc/scsi.
However, only 2 of them are listed in /proc/scsi/scsi
(the 2 Y-E DATA floppy drives are listed; the Zip-100
drive is not listed).
"cat /proc/bus/usb/devices" often produces
"usb_control/bulk_msg: timeout" messages.
These all seem to be related to the
usb-storage driver accessing Zip and/or floppy
drives.
It also says "(truncated)" at the end of the
nearly 8 KB output because the /proc strings from all
of these devices overflows the 8 KB allocated space.
After modifying devices.c to use 16 KB for its proc
output, there is no "(truncated)" message and the
output is around 13 KB.
Could not unload usb-storage module (hangs system);
had to reboot system. Repeated and was able to unload
all modules OK.
c. using usb-ohci.o: (Entrega 4-port PCI-USB adapter)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
All keyboards and mice work.
All 3 usb-storage drives are found and listed in
/proc/scsi/scsi.
"cat /proc/bus/usb/devices" produced no HCD-induced
error messages. The 8 KB max. length problem is here
also, of course (but fixed for my test).
Unloaded all modules OK.
Still to do:
- hub tier-depth tests (tomorrow)
- cpia camera + HCD stability (I've seen some instability;
will report on it later.)
- increase maximum size of /proc/bus/usb/devices output
from 8 KB to 16 KB (comments ? make it dynamic ?)
/proc/bus/usb/devices output from each of these is
available if needed.
~Randy
___________________________________________________
|Randy Dunlap Intel Corp., DAL Sr. SW Engr.|
|randy.dunlap.at.intel.com 503-696-2055|
|NOTE: Any views presented here are mine alone |
|and may not represent the views of my employer. |
|_________________________________________________|
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