Bug 8433

Summary: usb_suspend and scanner canoscan n670u
Product: Drivers Reporter: Elmar Neugebuer (elmar_n)
Component: USBAssignee: Alan Stern (stern)
Status: CLOSED CODE_FIX    
Severity: normal CC: protasnb, stern
Priority: P2    
Hardware: i386   
OS: Linux   
Kernel Version: 2.6.20, 2.6.21-git~ Subsystem:
Regression: --- Bisected commit-id:
Bug Depends on:    
Bug Blocks: 7216    
Attachments: dmesg1
lsusb

Description Elmar Neugebuer 2007-05-06 02:47:30 UTC 
Most recent kernel where this bug did *NOT* occur:
Distribution: ubuntu 7.04
Hardware Environment: scanner canoscan n670u
Software Environment:
Problem Description:

Is a usual problem with scanner and usb_suspend. The differenc is after scanner
is attached it is not working if i disable autosuspend ( echo -1 >
/sys/module/usbcore/parameters/autosuspend ) it's not working too. But if i plug
out scanner, disable autosupend, plugin and enable autosupend agene ewerything
working.

May be there is nothing bother about and just blacklist my scanner for usb_suspend.
Comment 1 Elmar Neugebuer 2007-05-06 02:48:26 UTC 
Created attachment 11403 [details]
dmesg1

here is dmesg after boot and with enabled autosuspend
Comment 2 Elmar Neugebuer 2007-05-06 02:50:09 UTC 
Created attachment 11404 [details]
lsusb

here is verbose lsusb. but if you like shor way take just this:
Bus 001 Device 008: ID 04a9:220d Canon, Inc. CanoScan N670U/N676U/LiDE 20
Comment 3 Alan Stern 2007-05-06 15:18:59 UTC 
From the dmesg1 log, it looks like you set the autosuspend delay to 0.  That's
not a good idea; it generates lots of unnecessary suspends and resumes.  Try
leaving it at the default value of 2.

By the way, you should realize that

    echo -1 > /sys/module/usbcore/parameters/autosuspend

doesn't really disable autosuspend.  Rather, it causes autosuspend to be
disabled for new devices as they are plugged in -- but it doesn't affect the
setting for devices that are already attached.  To disable autosuspend for a
particular device you should do:

    echo -1 >/sys/bus/usb/devices/XXX/power/autosuspend

where XXX is the sysfs pathname of your device (in this case 1-2).

It would be interesting to see if the scanner really does need to be blacklisted
for suspend.  You can test that: write -1 to the usbcore parameter, then plug in
the scanner, then set the scanner's autosuspend delay to 2 and wait for it to be
suspended.  Then see if it still works.
Comment 4 Natalie Protasevich 2007-06-14 10:55:25 UTC 
Elmar, did you have chance to try recommendations in #3?
Thanks!
Comment 5 Rafael J. Wysocki 2007-08-08 10:14:15 UTC 
Well, I think we have not received sufficient information from the reporter.
Comment 6 Alan Stern 2007-08-08 12:31:56 UTC 
We have found that many, many scanners don't like to be suspended.  The current development kernel has a blacklist entry for this scanner.  In the end we may blacklist the entire class.

Elmar, do you have anything new to report?  Otherwise this bug report will be closed in a few days.
Comment 7 Rafael J. Wysocki 2007-09-12 10:06:03 UTC 
(In reply to comment #6)
> Elmar, do you have anything new to report?  Otherwise this bug report will be
> closed in a few days.

Can you close it, please?
Comment 8 Alan Stern 2007-09-12 11:18:57 UTC 
The scanner in question has been added to the quirks list.  Closing the bug report.