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
