Theodore Kilgore wrote: > > Working on a driver for the Sonix SN9C2028 dual-mode cameras, I am > confronted with the situation that certain usb_control_msg() functions > are failing and returning -32. Does anyone know how to look up what -32 > is supposed to mean? It appears not to be in the standard errno.h file, > so it would apparently be somewhere else. And the on-line man page for > usb_control_msg does not seem totally helpful. It says > > "If successful, it returns the number of bytes transferred; otherwise, > it returns a negative error number." > > but does not otherwise discuss the negative error numbers. > > However, I am getting things like > > f60a5680 1488371641 S Ci:5:022:0 s c1 00 0001 0000 0001 1 < > f60a5680 1488373478 C Ci:5:022:0 -32 1 = 0c > > using from the camera, and I do not quite know why. Incidentally, quite > aside from the error message, the returned value is also a bit screwy. > It ought to be 00 and for no obvious reason it is not. However, even if > the returned value is correct, which also can sometimes happen, the > error is still there. > > Also the debug statement from dmesg consistently says (the corresponding > function is called read1) > > sn9c20: read1 error -32 > > But, what is essentially the same command works just fine in libgphoto2, > giving debug output which looks like this > > f14ca880 2936498715 S Ci:5:023:0 s c1 00 0001 0000 0001 1 < > f14ca880 2936499630 C Ci:5:023:0 0 1 = 00 > > which shows no error and is doing what it should. > > So if someone knows where the declarations of these error codes are, it > might help me to track down what the problem is. You'll need to look in 2 places. Documentation/usb/error-codes.txt uses named error codes and include/asm-generic/errno*.h converts names<->numbers. So 32 is EPIPE (from errno-base.h) and error-codes.txt tells what EPIPE is used for in usb-land. -- ~Randy LPC 2009, Sept. 23-25, Portland, Oregon http://linuxplumbersconf.org/2009/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
