On Wed, 2006-09-13 at 13:29 +0200, Wittawat Yamwong wrote: > Hello, > > I think that how sanei_usb_open() collects endponts is not correct. It loops > through all configurations, interfaces and alternate settings and takes the > first bulk in, bulk out and interrupt endpoint it found. This works only for > some special cases and it is likely to fail for multifunction devices, e.g. > Smartbase MP360 which has endpoints for the scanner function in the interface > #1. > > I would propose that sanei_usb_open() accepts two additional parameters > specifying an interface number and an alternate setting. These parameters can > be omitted (e.g. set to -1). In this case the behaviour described above is > valid. If the parameters are given, sanei_usb_open() must use only the > endpoints belonging to the specified interface. > > There is also an issue with sanei_usb_set_configuration(), it simply doesn't > work this way because setting new configuration will succeed if and only if > there is no interfaces claimed by any driver. But the function takes the > device number returned by sanei_usb_open() as a parameter and, unfortunely, > sanei_usb_open() implicitly claims one interface. We have chicken and egg > problem here. Solution: sanei_usb_set_configuration() have to take the device > name instead of the device number as the first parameter. > > If I understand correctly, sanei_usb_claim_interface(), > sanei_usb_release_interface() and sanei_usb_set_altinterface() are useless > because sanei_usb_open() already claims an interface for you and > sanei_usb_close() will release it afterward. Why does one want to claim > another interface while he cannot use its endpoints through sanei_usb > functions? > > Regards > -- > Wittawat Yamwong > Hannover, Germany > I use them for my stv680 backend, one problem i had after some updates (sane, libusb,kernel) was that setting the configuration didn't work anymore. Disable of the set_configuration solved it for me at that moment. If setting the configuration is needed for other devices, i don't know at the moment if some of the webcams i have need that.
The above lines from some earlier email this year. I think a table generation with the selectable values for the configuration, interface and altsetting and then choice which values are needed will probaly solve some of the present problems when selecting a device and perform a bulk read. Depending on the function of a (for example) webcam (image size etc) selecting a different altsetting for reading (packet size) data should be possible (or an option which will be implemented later) Some usb devices have also for one altsetting 2 bulk read in endpoints to make it more complex. I don't know if somebody already made some code for these proposals and did some testing or has some other comment but i think a update for these 2 functions is an improvement (sanei_usb_open and sanei_usb_set_configuration) -- -------- m.vr.gr. Gerard Klaver