Date: Wed, 04 Aug 2004 21:17:19 -0400 From: Chris <chris@tellme3times.com> To: ticso@cicely.de Cc: freebsd-current@freebsd.org Subject: Re: USB drivers Message-ID: <41118A9F.8030302@tellme3times.com> In-Reply-To: <20040804150738.GE20488@cicely12.cicely.de> References: <4110F5AE.6030403@tellme3times.com> <20040804150738.GE20488@cicely12.cicely.de>
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Bernd Walter wrote: >On Wed, Aug 04, 2004 at 10:41:50AM -0400, Chris wrote: > > >>The last time I programed was over 15 years ago and I was thinking of >>looking into the USB drivers for FreeBSD concerning multifunction >>devices. If I ask stupid questions forgive me because I am seeing this >>as a user. >> >>First I would like to know if there is a technical reason why two >>different divers cannot attach to the same device. If each driver works >>well independently, what is the reason to prevent the second one from >>attaching? I would assume that if you attempted to use both drivers at >>the same time you would get a device busy error. >> >> > >USB devices can be designed to have multiple interfaces at which you >can have different drivers - e.g. you can have a ulpt/umass combo >and both drivers just clain the according interface from the same >device. >Therefor also drivers can be programmed for whole USB devices and for >USB subdevices. >This works perfectly with FreeBSD. > > > >>Am I misunderstanding something here? I see ulpt: and unlpt: attaching >>to the same device and the choice of which one to use is up to the user >>and the hardware they have. If we have two drivers attach in one case >>why, and where, do we prevent other drivers from attaching if they meet >>the minimum requirements? >> >> > >unlpt and ulpt are just different representations from the same driver. >There is absolutely no sense in having two clients printing at the same >time on the same printer, so blocking each other is absolutely reasonable. >Scheduling multiple requests is up to software like lpd. >See ulpt(4) for details about the functional difference in ulpt vs. unlpt >device nodes - depending on the printer you will likely end up in always >using the same devicenode. >Why do you think this is wrong? > > What I am looking to accomplish is to attach uscanner and ulpt to an EPSON CX5400. While each driver works great by itself I am unable to attach both at the same time. I was told on this list that we may not attach two drivers to the same device. If this is not correct then I would appreciate a little help in attaching existing drivers or writing a new one. Chris
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