Hi Jean-Philippe, On Tuesday 08 February 2011 16:13:56 jean-philippe francois wrote: > Hi, > > With the current uvc code, class specific setup request are redirected > to userspace. > However, in order to decode these request, userspace needs some > information, that are currently available in the gadget descriptor. Which > is kernel code. > > Let's take an example request : > > bRequestType = 0xa1 > bRequest = 0x87 (UVC_GET_DEF) > wValue = 0x200; > wIndex = 0x200; > wLength = 2; > > wIndex is (UnitId | Interface) > > Interface = 0 means control interface. > Now, to translate wValue into a CS (Control Selector Code), I need to map > UnitId to an entity type. > > To do this, I can look in the driver/usb/gadget/webcam.c file, and > find the answer : > UnitID = 2 means processing unit. > > I can (and will) hardcode this mapping (UnitId = 2 <=> Processing Unit) in > my userspace setup request handling code. > > But then I make a camera with two input unit, a selector unit, > and my userspace code is broken :( > > What's the plan for future enhancement of this code ?
webcam.c is sample code only. For real-world applications you're supposed to write your own gadget driver than instanciates a UVC function, and develop a userspace application (which can be based on uvc-gadget - note the GPL license though) that matches your driver. There's currently no plan to export the descriptors to the application. Do you think that would be useful ? -- Regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
