Re: [PATCH 1/1] V4L: stk11xx, add a new webcam driver

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Mauro Carvalho Chehab a écrit :
This seems to be an interesting approach.

Interesting but impossible to do for ioctl calls.
When the application does a ioctl(fd_of_mnt_video0,VIDIOC_G_FMT,&arg) for example, there is no way for the userspace helper to catch this ioctl. The application could only open/read from the userspace helper's file /mnt/video0.
ioctl would still have to be done on the kernel device driver.
I thought also about a /proc interface for decompression algorithms (a helper would listen on a /proc file and write on another /proc file) but /proc is not designed for that kind of thing.
A separate library seems to be the simplest solution.

There are some ways for this to work. For example, you may create a
helper device for the daemon driver to bind, even requiring it to have
root permission.

Right, but I am afraid that complex userspace/kernelspace context changes breaks performance.
Nevertheless, I will start to specify the framework.
The helper daemon would link to the v4l2-apps/lib.
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