Hi everybody, I came across a device which exposes class specific interface descriptors (CS_INTERFACE) that the current Linux kernel code can't parse.
Most USB devices describe the class specific interface data between the interface descriptor and its associated endpoint descriptors: INTERFACE CS_INTERFACE CS_INTERFACE CS_INTERFACE CS_INTERFACE ENDPOINT 2 The device I'm trying to use returns the CS_INTERFACE descriptors after the endpoint descriptors: INTERFACE ENDPOINT 2 CS_INTERFACE CS_INTERFACE CS_INTERFACE CS_INTERFACE Is this legal ?All examples found in USB specification documents put the CS_INTERFACE descriptors between the INTERFACE and ENDPOINT descriptors, but I found no mention of this being a requirement. The interface descriptor parsing code (usb_parse_interface in drivers/usb/core/config.c) stores a pointer to those extra data in the struct usb_host_interface 'extra' field. It currently only handles extra data between INTERFACE and ENDPOINT descriptors. All descriptors after the endpoint descriptors are just skipped. Is this something we should fix ? If the extra data can be interleaved with other descriptors, a single pointer won't be enough. It should be easy to set the extra field to point to extra data after the endpoint descriptors, but it won't work if class specific interface descriptors are interleaved with endpoint descriptors. Best regards, Laurent Pinchart ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
