On 21/09/2010 23:01, Chris Frey wrote: > On Tue, Sep 21, 2010 at 12:12:57PM +0100, Toby Gray wrote: >> However there's clearly a reason for the call to usb_set_altinterface, >> so can anyone remember what devices it was necessary for? > It wasn't a specific device, it was all devices, I believe. It was to work > around a change in the kernel, which caused odd timeout issues. Also, > this fix made things work on Mac OSX and FreeBSD. > > The usb_set_altinterface() call is the only one in libusb that > works directly with the interface, as far as I can tell. > > You can read the long, painstaking thread here. I ended up doing > a git-bisect on the kernel to find the spot where it was having trouble. > > http://marc.info/?t=123554440300001&r=1&w=2 > > Especially here, where Alan Stern says that calling set_altinterface() > should always be safe. > > http://marc.info/?l=linux-usb&m=123627088604495&w=2 > Thanks for those links. It sounds like setting the alternate setting to 0 for the interface is needed to make the connection work reliably, but that setting the alternate setting when URBs are outstanding on the other (usb-storage) interface really confuses most BlackBerry devices (although luckily not newer OSv5 ones as far as I can tell).
It's odd that I don't see the original issue described in the above thread on my Ubuntu 10.04 machine running 2.6.32, but as it was always a timing related issue that doesn't seem too surprising. >> Depending on the history of that call and what devices it was needed >> for, I'd suggest doing one of the following: >> 1) Removing the call to it entirely >> 2) Only call it if there are multiple alternate settings >> 3) Add it as an option for the various tools and API users >> 4) Carry on calling it but using a bAlternateSettings value retrieved >> from the device; this won't fix the mass storage issue but will fix the >> Barry code. >> >> What do people think? > I think someone needs to reproduce the original problem from 2009, and > see if option 2 would be a suitable fix, for Linux, Mac OSX, and FreeBSD. :-) I don't think option 2 will help. I've tried a range of BlackBerry devices and none of them seem to have more than 1 alternate settings. I'll have a more detailed look to see if there's some other way around this, although without being able to reproduce the original reason for calling usb_set_altinterface() that might be a bit tricky. So I'll probably try setting up a VM with a 2.6.28 kernel and see if I can reproduce the issue on there. Regards, Toby ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Barry-devel mailing list Barry-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/barry-devel
