Hi Hans,
>> +/*
>> + * Analog Devices video display driver
>> + *
>> + * Copyright (c) 2011 Analog Devices Inc.
>
> Analog Devices? What has this to do with Analog Devices?
>
I wrote this driver for Analog Devices Blackfin.
>> +
>> +static int disp_mmap(struct file *file, struct vm_area_struct *vma)
>> +{
>> + struct disp_device *disp = video_drvdata(file);
>> + int ret;
>> +
>> + if (mutex_lock_interruptible(&disp->mutex))
>> + return -ERESTARTSYS;
>> + ret = vb2_mmap(&disp->buffer_queue, vma);
>> + mutex_unlock(&disp->mutex);
>> + return ret;
>> +}
>> +
>> +#ifndef CONFIG_MMU
>> +static unsigned long disp_get_unmapped_area(struct file *file,
>> + unsigned long addr,
>> + unsigned long len,
>> + unsigned long pgoff,
>> + unsigned long flags)
>> +{
>> + struct disp_device *disp = video_drvdata(file);
>> + int ret;
>> +
>> + if (mutex_lock_interruptible(&disp->mutex))
>> + return -ERESTARTSYS;
>> + ret = vb2_get_unmapped_area(&disp->buffer_queue,
>> + addr,
>> + len,
>> + pgoff,
>> + flags);
>> + mutex_unlock(&disp->mutex);
>> + return ret;
>> +}
>> +#endif
>> +
>> +static unsigned int disp_poll(struct file *file, poll_table *wait)
>> +{
>> + struct disp_device *disp = video_drvdata(file);
>> + int ret;
>> +
>> + mutex_lock(&disp->mutex);
>> + ret = vb2_poll(&disp->buffer_queue, file, wait);
>> + mutex_unlock(&disp->mutex);
>> + return ret;
>> +}
>
> Use the helper functions in media/videobuf2-core.h for these file ops.
>
OK, I will use vb2_fop_mmap. But I'm not sure if I need to lock it.
>> +static int disp_reqbufs(struct file *file, void *priv,
>> + struct v4l2_requestbuffers *req_buf)
>> +{
>> + struct disp_device *disp = video_drvdata(file);
>> + struct vb2_queue *vq = &disp->buffer_queue;
>> + struct v4l2_fh *fh = file->private_data;
>> + struct disp_fh *disp_fh = container_of(fh, struct disp_fh, fh);
>> +
>> + if (vb2_is_busy(vq))
>> + return -EBUSY;
>> +
>> + disp_fh->io_allowed = true;
>
> There is no need for io_allowed. The vb2_is_busy() function does the same
> thing. It saves a lot of code since you now can just use v4l2_fh instead of
> disp_fh, which allows you to use even more helper functions (v4l2_fh_open and
> v4l2_fh_release for starters).
>
> In fact, you can use all the vb2 ioctl helpers saving you a lot of code.
>
I don't think so. vb2_is_busy can't check if this file instance has
the right to stream off output.
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