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Date: Sat, 11 Jun 2011 09:30:24 +0800
Message-ID: <BANLkTinAfB_jiS+6f8Dqt4ZEK19ndv_nDA@mail.gmail.com>
Subject: Re: Improving kernel -> userspace (usbfs) usb device hand off
From: Xiaofan Chen <xiaofanc@gmail.com>
To: Theodore Kilgore <kilgota@banach.math.auburn.edu>
Cc: linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
	libusb-devel@lists.sourceforge.net
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On Sat, Jun 11, 2011 at 6:43 AM, Theodore Kilgore
<kilgota@banach.math.auburn.edu> wrote:
> I do not believe that we have found the optimal solution, yet. The ideal
> thing would be some kind of hack which allows the kernel to be used when
> it is needed, and when it is not needed it does not interfere.

Just wondering if you can use libusb-1.0 for the user space still image
functionality.

libusb-1.0 offers the following functions to do that for you under Linux.

int 	libusb_kernel_driver_active (libusb_device_handle *dev, int interface)
 	Determine if a kernel driver is active on an interface.
int 	libusb_detach_kernel_driver (libusb_device_handle *dev, int interface)
 	Detach a kernel driver from an interface.
int 	libusb_attach_kernel_driver (libusb_device_handle *dev, int interface)
 	Re-attach an interface's kernel driver, which was previously
detached using libusb_detach_kernel_driver().

So you can detach the kernel v4l2 driver at the beginning and later
re-attach it when you finish.

-- 
Xiaofan