Hello
I am trying to write a driver for my usb camera.
The problem is that i can't understand what goes wrong every time the driver
tries to write to a register to send a command (no data on return). This is
the function:
static int my_set_reg(struct usb_device *udev, __u16 value, __u16 index)
{
int err;
err = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
0,
USB_TYPE_VENDOR | USB_DIR_OUT,
value, index, NULL, 0, HZ);
if (err)
printk(KERN_DEBUG "MY_DRIVER: my_set_reg() failed "
"(value %04X, index %02X).\n", value, index);
return err;
}
A tipical call is my_set_reg(0x0010, 0x0000);
Can someone explain me what values the third parameter can *exactly* assume?
I think "0" means something like "set control transfer".
Since i don't want data on return, Is NULL right (4th parameter) ?
Is "size" parameter right too?
I tried everything but the function always fails, and the kernel disconnects()
and probes() again without any reason (weird):
usb-uhci.c: interrupt, status 2, frame# 862
MY_DRIVER: my_set_reg() failed (value 0010, index 00).
hub.c: already running port 1 disabled by hub (EMI?), re-enabling...
usb.c: USB disconnect on device 00:07.2-1 address 20
MY_DRIVER: disconnect() called.
hub.c: new USB device 00:07.2-1, assigned address 21
usb.c: USB device not accepting new address=21 (error=-110)
hub.c: new USB device 00:07.2-1, assigned address 22
MY_DEVICE: probe() called.
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