unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
loff_t *ppos, int nonblock);
-size_t vb2_write(struct vb2_queue *q, char __user *data, size_t count,
+size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
loff_t *ppos, int nonblock);
/**
int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
int vb2_fop_release(struct file *file);
-ssize_t vb2_fop_write(struct file *file, char __user *buf,
+ssize_t vb2_fop_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos);
ssize_t vb2_fop_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos);