Date: Tue, 25 Nov 2003 10:53:29 +0100 From: Toni Andjelkovic <toni@soth.at> To: Dan Langille <dan@langille.org> Cc: hackers@freebsd.org Subject: Re: using devel/libusb to access USB Message-ID: <20031125095329.GB1975@acme.soth.at> In-Reply-To: <3FC1CEA0.28542.14DD8CEF@localhost> References: <3FC1CEA0.28542.14DD8CEF@localhost>
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On Mon, Nov 24 2003 (09:25:52 -0500), Dan Langille wrote: > We have been looking at the devel/libusb port and experimenting with > testlibusb which is a part of that port. We have noticed that > usb_find_devices() does not find any devices. Looking at the usb.c > code within libusb, we found that usb_os_find_devices() does not > return any devices, and therefore the while loop is never entered. > > We tracked the problem down to usb_os_find_devices() (within bsd.c) > and found that various things were preventing the list from being > created. I have experienced a similar problem a few months ago. I've tracked it to ugenopen() in sys/dev/usb/ugen.c, which returned EBUSY if the control endpoint /dev/ugen0 was already open. Consequently, usb_find_devices() failed to return anything useful. However, as Bernd Walter suggested in a recent posting to hackers@, this could be avoided by using interface specific endpoints (/dev/ugen?.?) instead of the control endpoint (/dev/ugen?) for communication. Cheers, Toni
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