Re: file_storage gadget requires a sync...

On Tue, 5 Jun 2007, Alan Stern wrote:

> On Tue, 5 Jun 2007, Guennadi Liakhovetski wrote:
> 
> > I see a ~100% reproducible problem under 2.6.20 with g_file_storage: the 
> > script
> > 
> > cp fs.image /tmp/
> > modprobe g_file_storage file=/tmp/fs.image
> > 
> > comes with no error back, but the enumeration fails. Whereas inserting a 
> > sync between the "cp" and "modprobe" fixes it... It worked without sync 
> > under 2.4.30. Filesystem is ext3 mounted with default parameters 
> > (rw,data=ordered), gadget driver net2280, i386 platform. Is this intended 
> > behaviour?
> 
> Yes, of course we always write device drivers so that they will fail in 
> unexpected ways unless the user does something unintuitive and 
> undocumented.  :-)

Sure, I always program that way too:-)

> When you say the enumeration fails, what exactly goes wrong?  I've 
> never tried using g_file_storage with a newly-created backing file.

Ok, the host says:

usb usb1: wakeup_rh (auto-start)
hub 1-0:1.0: state 7 ports 2 chg 0000 evt 0004
uhci_hcd 0000:00:1f.2: port 2 portsc 0093,00
hub 1-0:1.0: port 2, status 0101, change 0001, 12 Mb/s
hub 1-0:1.0: debounce: port 2: total 100ms stable 100ms status 0x101
usb 1-2: new full speed USB device using uhci_hcd and address 69
usb 1-2: default language 0x0409
usb 1-2: new device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-2: Product: File-backed Storage Gadget
usb 1-2: Manufacturer: Linux 2.6.20.1-rt8-dsa-mftd2x-2 with net2280
usb 1-2: SerialNumber: 3238204E6F76
usb 1-2: uevent
usb 1-2: configuration #1 chosen from 1 choice
usb 1-2: khubd timed out on ep0out len=0/0
usb 1-2: can't set config #1, error -110
drivers/usb/core/inode.c: creating file '069'
hub 1-0:1.0: state 7 ports 2 chg 0000 evt 0004

and on USB-analyser I see an invalid out-transaction with an "invalid 
toggle" and a setup transactio with only NAKs.

Thanks
Guennadi
---------------------------------
Guennadi Liakhovetski, Ph.D.
DSA Daten- und Systemtechnik GmbH
Pascalstr. 28
D-52076 Aachen
Germany

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