[sane-devel] sanei_usb limitations

[Hugo "Bonstra" Grostabussiat]

Hi,
as I said in my last post, I am writing a backend for Hercules Scan at home
48 USB scanner.
This device uses an unusual USB interface which has 3 bulk endpoints:
* EP 0x01 is used to send commands to device
* EP 0x82 is used to get the result of some commands
* EP 0x83 is used to get scan data
In its current state however, sanei_usb API does not allow us to choose
what endpoint to use for bulk transfers. It will always use the first IN
and OUT endpoints it finds for functions sanei_usb_read_bulk() ans
sanei_usb_write_bulk() respectively.

To overcome that limitation, I thought of adding a few functions to
sanei_usb API to allow specifying an alternative endpoint (for instance:
sanei_usb_read_bulk_ep() which would take an additional ep argument of
type SANE_Byte). It wouldn't break any existing backend.
Would a change of that kind be accepted ? Or should I use libusb directly ?

Thanks in advance.
---
Hugo Grostabussiat