On Thu, Dec 11, 2008 at 04:06:24PM -0500, m. allan noah wrote: > On Mon, Dec 1, 2008 at 10:23 PM, ABC <abc at telekom.ru> wrote: > > First of all sanei_usb_init() is not designed to be used for rescanning > > after any other sanei_usb functions is called. It is just initialization > > and rescanning ability is not documented side effect. As stated in > > documentation: "Call this before any other sanei_usb function". So don't > > call it after. (This doesn't state it should be called just once, so we > > could rescan before first device is opened.) > > sanei_usb_init() will blast the existing info, and assign all new > device indexes to whatever it finds.
Exactly how it works now. > However, sanei_usb_init() is only > called by backends in sane_init() and sane_get_devices(). A frontend > will only call sane_init() once, so that is not a problem, and the > sane standard says this about sane_get_devices(): > > The returned list is guaranteed to remain unchanged and valid until > (a) another call to this function is performed or (b) a call to > sane_exit() is performed. This don't says calling sane_get_devices will or should break any already opened device. > So, if you call sane_get_devices() twice, you cannot complain that any > devices you have open don't work anymore. I can complain about that, since list of name/vendor/model/type of all available devices is logically not related to any already opened device. > However, you have a valid point that most backends only call > sanei_usb_init() in sane_init(), and I think that should change. In backend I'm writing I call sanei_usb_init multiple times (in each sane_get_devices) only if I don't have opened devices. I think that's ok.
