Hi Ezequiel 2012/2/25 Ezequiel García <elezegarcia@gmail.com>:

Hi,

If I register a video device with this fops:

static const struct v4l2_file_operations v4l2_fops = {        .owner      = THIS_MODULE,        .open        = xxx_open,        .unlocked_ioctl = xxx_unlocked_ioctl,        .poll           = xxx_poll,        .mmap      = xxx_mmap, };

then if I "cat" the device

$ cat /dev/video0

Who is supporting read() ?

I thought it could be v4l2_read(), however this function seems to return EINVAL:

static ssize_t v4l2_read(struct file *filp, char __user *buf,                size_t sz, loff_t *off) {        struct video_device *vdev = video_devdata(filp);        int ret = -ENODEV;

       if (!vdev->fops->read)                return -EINVAL;        if (vdev->lock && mutex_lock_interruptible(vdev->lock))                return -ERESTARTSYS;        if (video_is_registered(vdev))                ret = vdev->fops->read(filp, buf, sz, off);        if (vdev->lock)                mutex_unlock(vdev->lock);        return ret; }

I'm not all that familiar with v4l, but based on what you've posted, you need to populate the read routine in your v4l2_fops structure to support read. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com