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.
Theodore Kilgore
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