Re: [Libusb-devel] Patch: libusb/os/linux_usbfs.c: Distingush between usbfs and other kernel mode drivers

[Peter S. <pe...@st...>]

Xiaofan Chen wrote:
> >> I just wonder why "usbfs" is returned as the kernel driver.
> >
> > It *is* the name of the kernel driver. ;)
> >
> >> Probably that should be fixed (in the kernel or in libusb).
> >
> > Why is it wrong?
> 
> I do not think "usbfs" is a valid kernel driver name.

It *is* the name of the kernel driver which is handling the device..

Just like Windows needs libusb0.sys or WinUSB.sys Linux needs usbfs.
If I build a kernel *without* usbfs (CONFIG_USBFS=n) then I will not
be able to use libusb with that kernel.


When I attach a device of mine, here's what
/sys/kernel/debug/usb/devices looks like:

T:  Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=ff(vend.) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=ffff ProdID=0004 Rev= 0.02
S:  Manufacturer=foo
S:  Product=bar
S:  SerialNumber=p2
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=00 Prot=ff Driver=(none)
E:  Ad=81(I) Atr=03(Int.) MxPS=  23 Ivl=10ms

While running a libusb program that has that interface open, it
changes a little:

T:  Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=ff(vend.) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=ffff ProdID=0004 Rev= 0.02
S:  Manufacturer=foo
S:  Product=bar
S:  SerialNumber=p2
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=00 Prot=ff Driver=usbfs
E:  Ad=81(I) Atr=03(Int.) MxPS=  23 Ivl=10ms

And when I stop that program, it goes back:

T:  Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=ff(vend.) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=ffff ProdID=0004 Rev= 0.02
S:  Manufacturer=foo
S:  Product=bar
S:  SerialNumber=p2
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=00 Prot=ff Driver=(none)
E:  Ad=81(I) Atr=03(Int.) MxPS=  23 Ivl=10ms

Also note /sys/bus/usb/drivers/usbfs/


//Peter