On Tue, May 18, 2010 at 8:13 PM, Thomas Jarosch
<thomas.jarosch@xxxxxxxxxxxxx> wrote:
> On Tuesday, 18. May 2010 13:43:53 Xiaofan Chen wrote:
>> That is exactly right. And I think failure to detach the kernel driver is
>> quite normal (eg: you already run libftdi once and the kernel driver
>> is already detached) and should not return error. A warning is enough.
>>
>> ret = libusb_detach_kernel_driver(ftdi->usb_dev, ftdi->interface);
>> if (ret < 0 && ret != LIBUSB_ERROR_NOT_FOUND)
>> ftdi_error_return(-11, "libusb_detach_kernel_driver () failed");
>
> That's the reason we already ignore LIBUSB_ERROR_NOT_FOUND ;) I never had
> trouble with the detach code. If the detach really fails
> (except _NOT_FOUND and _NOT_SUPPORTED), then we should abort with an error.
You are probably right. The above patch is not really right though since
it does not ignore LIBUSB_NOT_SUPPORTED (Darwin/Windows libusb-1.0
will return this error code).
Take note that the return codes can be others under Linux. But I believe
you are right that ENODATA (for libusb-0.1) and
LIBUSB_ERROR_NOT_FOUND (for libusb-1.0) are not real errors.
The other three situation are probably real errors.
>From libusb-1.0 linux_usbfs.c:
static int op_detach_kernel_driver(struct libusb_device_handle *handle,
int interface)
{
int fd = __device_handle_priv(handle)->fd;
struct usbfs_ioctl command;
int r;
command.ifno = interface;
command.ioctl_code = IOCTL_USBFS_DISCONNECT;
command.data = NULL;
r = ioctl(fd, IOCTL_USBFS_IOCTL, &command);
if (r) {
if (errno == ENODATA)
return LIBUSB_ERROR_NOT_FOUND;
else if (errno == EINVAL)
return LIBUSB_ERROR_INVALID_PARAM;
else if (errno == ENODEV)
return LIBUSB_ERROR_NO_DEVICE;
usbi_err(HANDLE_CTX(handle),
"detach failed error %d errno %d", r, errno);
return LIBUSB_ERROR_OTHER;
}
return 0;
}
--
Xiaofan http://mcuee.blogspot.com
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