Hi everybody, I'm working on a USB gadget driver for a device that needs to report a bunch of class-specific descriptors. Those class descriptors do not depend on kernelspace code in the device driver. They merely expose capabilities of the device that are implemented in userspace. I thus would like to provide the USB gadget driver with those descriptors from a userspace application. I got this working for a single-function device by disconnecting from the bus in the bind() handler (usb_gadget_disconnect). The driver then waits until an application feeds it with descriptors through a sysfs file, and connects to the bus. I'm now porting the driver to the composite framework, and things get more complex. The composite framework expect the bind() handler to configure the descriptors. I thus need to have them available before the bind() handler is called, which means I need them before registering the composite driver with usb_composite_register(). The composite driver registers itself in its module initialization function. As no device structure is available at that point I can't create a sysfs or configfs file, nor can I use the firmware request API. procfs might be a solution, but it doesn't feel very clean for some reason. As this is my first USB gadget driver I could have got the architecture wrong. I'd appreciate any advice you could give me. Has someone worked on a driver with similar requirements before ? Are there guidelines I should follow ? Best regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
