Re: [PATCH RFC v2 3/7] v4l: add new tuner types for SDR

[Hans Verkuil <hverkuil@xs4all.nl>]

On 12/14/2013 05:15 PM, Antti Palosaari wrote:
> Define tuner types V4L2_TUNER_ADC and V4L2_TUNER_RF for SDR usage.
> 
> ADC is used for setting sampling rate (sampling frequency) to SDR
> device.
> 
> Another tuner type, named as V4L2_TUNER_RF, is possible RF tuner.
> Is is used to down-convert RF frequency to range ADC could sample.
> Having RF tuner is optional, whilst in practice it is almost always
> there.
> 
> Also add checks to VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY and
> VIDIOC_ENUM_FREQ_BANDS only allow these two tuner types when device
> type is SDR (VFL_TYPE_SDR).
> 
> Prohibit VIDIOC_S_HW_FREQ_SEEK explicitly when device type is SDR,
> as device cannot do hardware seek without a hardware demodulator.
> 
> Cc: Hans Verkuil <hverkuil@xs4all.nl>
> Signed-off-by: Antti Palosaari <crope@iki.fi>
> ---
>  drivers/media/v4l2-core/v4l2-ioctl.c | 42 ++++++++++++++++++++++++++----------
>  include/uapi/linux/videodev2.h       |  2 ++
>  2 files changed, 33 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index bc10684..6b72bd8 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1288,8 +1288,13 @@ static int v4l_g_frequency(const struct v4l2_ioctl_ops *ops,
>  	struct video_device *vfd = video_devdata(file);
>  	struct v4l2_frequency *p = arg;
>  
> -	p->type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> -			V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> +	if (vfd->vfl_type == VFL_TYPE_SDR) {
> +		if (p->type != V4L2_TUNER_ADC && p->type != V4L2_TUNER_RF)
> +			return -EINVAL;

This is wrong. As you mentioned in patch 1, the type field should always be set by
the driver. So type is not something that is set by the user.

I would just set type to V4L2_TUNER_ADC here (all SDR devices have at least an ADC
tuner), and let the driver change it to TUNER_RF if this tuner is really an RF
tuner. 

> +	} else {
> +		p->type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> +				V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> +	}
>  	return ops->vidioc_g_frequency(file, fh, p);
>  }
>  
> @@ -1300,10 +1305,16 @@ static int v4l_s_frequency(const struct v4l2_ioctl_ops *ops,
>  	const struct v4l2_frequency *p = arg;
>  	enum v4l2_tuner_type type;
>  
> -	type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> -			V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> -	if (p->type != type)
> -		return -EINVAL;
> +	if (vfd->vfl_type == VFL_TYPE_SDR) {
> +		if (p->type != V4L2_TUNER_ADC && p->type != V4L2_TUNER_RF)
> +			return -EINVAL;
> +		type = p->type;

No need to set type here. It isn't used.

> +	} else {
> +		type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> +				V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> +		if (type != p->type)
> +			return -EINVAL;
> +	}
>  	return ops->vidioc_s_frequency(file, fh, p);
>  }
>  
> @@ -1383,6 +1394,10 @@ static int v4l_s_hw_freq_seek(const struct v4l2_ioctl_ops *ops,
>  	struct v4l2_hw_freq_seek *p = arg;
>  	enum v4l2_tuner_type type;
>  
> +	/* s_hw_freq_seek is not supported for SDR for now */
> +	if (vfd->vfl_type == VFL_TYPE_SDR)
> +		return -EINVAL;
> +
>  	type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
>  		V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
>  	if (p->type != type)
> @@ -1882,11 +1897,16 @@ static int v4l_enum_freq_bands(const struct v4l2_ioctl_ops *ops,
>  	enum v4l2_tuner_type type;
>  	int err;
>  
> -	type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> -			V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> -
> -	if (type != p->type)
> -		return -EINVAL;
> +	if (vfd->vfl_type == VFL_TYPE_SDR) {
> +		if (p->type != V4L2_TUNER_ADC && p->type != V4L2_TUNER_RF)
> +			return -EINVAL;
> +		type = p->type;

Ditto.

> +	} else {
> +		type = (vfd->vfl_type == VFL_TYPE_RADIO) ?
> +				V4L2_TUNER_RADIO : V4L2_TUNER_ANALOG_TV;
> +		if (type != p->type)
> +			return -EINVAL;
> +	}

Perhaps this type check should be moved to a separate function. It's after
all used by both enum_freq_bands and s_frequency.

>  	if (ops->vidioc_enum_freq_bands)
>  		return ops->vidioc_enum_freq_bands(file, fh, p);
>  	if (is_valid_ioctl(vfd, VIDIOC_G_TUNER)) {
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index b8ee9048..c3e7780 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -159,6 +159,8 @@ enum v4l2_tuner_type {
>  	V4L2_TUNER_RADIO	     = 1,
>  	V4L2_TUNER_ANALOG_TV	     = 2,
>  	V4L2_TUNER_DIGITAL_TV	     = 3,
> +	V4L2_TUNER_ADC               = 4,
> +	V4L2_TUNER_RF                = 5,
>  };
>  
>  enum v4l2_memory {
> 

Regards,

	Hans