Re: [PATCHv4 24/25] [media] cx231xx: enable tuner->decoder link at videobuf start

[Hans Verkuil <hverkuil@xs4all.nl>]

On 02/13/2015 11:58 PM, Mauro Carvalho Chehab wrote:
> The tuner->decoder needs to be enabled when we're about to
> start streaming.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> 
> diff --git a/drivers/media/usb/cx231xx/cx231xx-video.c b/drivers/media/usb/cx231xx/cx231xx-video.c
> index f3d1a488dfa7..634763535d60 100644
> --- a/drivers/media/usb/cx231xx/cx231xx-video.c
> +++ b/drivers/media/usb/cx231xx/cx231xx-video.c
> @@ -703,6 +703,74 @@ static void free_buffer(struct videobuf_queue *vq, struct cx231xx_buffer *buf)
>  	buf->vb.state = VIDEOBUF_NEEDS_INIT;
>  }
>  
> +static int cx231xx_enable_analog_tuner(struct cx231xx *dev)
> +{
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +	struct media_device *mdev = dev->media_dev;
> +	struct media_entity  *entity, *decoder = NULL, *source;
> +	struct media_link *link, *found_link = NULL;
> +	int i, ret, active_links = 0;
> +
> +	if (!mdev)
> +		return 0;
> +
> +/*
> + * This will find the tuner that it is connected into the decoder.
> + * Technically, this is not 100% correct, as the device may be using an
> + * analog input instead of the tuner. However, we can't use the DVB for dvb

'we can't use the DVB for dvb'?? You probably mean 'can't use the DVB API'.

> + * while the DMA engine is being used for V4L2.
> + */

Weird indentation, should be one to the right.

> +	media_device_for_each_entity(entity, mdev) {
> +		if (entity->type == MEDIA_ENT_T_V4L2_SUBDEV_DECODER) {
> +			decoder = entity;
> +			break;
> +		}
> +	}
> +	if (!decoder)
> +		return 0;
> +
> +	for (i = 0; i < decoder->num_links; i++) {
> +		link = &decoder->links[i];
> +		if (link->sink->entity == decoder) {
> +			found_link = link;
> +			if (link->flags & MEDIA_LNK_FL_ENABLED)
> +				active_links++;
> +			break;
> +		}
> +	}
> +
> +	if (active_links == 1 || !found_link)
> +		return 0;
> +
> +	source = found_link->source->entity;
> +	for (i = 0; i < source->num_links; i++) {
> +		struct media_entity *sink;
> +		int flags = 0;
> +
> +		link = &source->links[i];
> +		sink = link->sink->entity;
> +
> +		if (sink == entity)
> +			flags = MEDIA_LNK_FL_ENABLED;
> +
> +		ret = media_entity_setup_link(link, flags);
> +		if (ret) {
> +			dev_err(dev->dev,
> +				"Couldn't change link %s->%s to %s. Error %d\n",
> +				source->name, sink->name,
> +				flags ? "enabled" : "disabled",
> +				ret);
> +			return ret;
> +		} else
> +			dev_dbg(dev->dev,
> +				"link %s->%s was %s\n",
> +				source->name, sink->name,
> +				flags ? "ENABLED" : "disabled");
> +	}
> +#endif
> +	return 0;
> +}
> +
>  static int
>  buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
>  	       enum v4l2_field field)
> @@ -756,6 +824,9 @@ buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
>  	}
>  
>  	buf->vb.state = VIDEOBUF_PREPARED;
> +
> +	cx231xx_enable_analog_tuner(dev);

Is this the right place? Isn't this now called for every QBUF? I would expect this
to happen when you start streaming.

In vb2 it would be in start_streaming(), of course.

Regards,

	Hans

> +
>  	return 0;
>  
>  fail:
> 

Regards,

	Hans