linux-kernel - Re: [PATCH 17/31] media: au0828 video change to use v4l_enable_media

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Date:	Thu, 28 Jan 2016 13:57:52 -0200
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	tiwai@...e.com, clemens@...isch.de, hans.verkuil@...co.com,
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Subject: Re: [PATCH 17/31] media: au0828 video change to use
 v4l_enable_media_tuner()

Em Wed,  6 Jan 2016 13:27:06 -0700
Shuah Khan <shuahkh@....samsung.com> escreveu:

> au0828 is changed to use v4l_enable_media_tuner() to check for
> tuner availability from vidioc_g_tuner(), and au0828_v4l2_close(),
> before changing tuner settings. If tuner isn't free, return busy
> condition from vidioc_g_tuner() and in au0828_v4l2_close() tuner
> is left untouched without powering down to save energy.

Did you test the code when the input is not a tuner, but, instead,
Composite or S-Video connector, as shown at:
	https://mchehab.fedorapeople.org/mc-next-gen/au0828.png

I guess calling it v4l-enable_media_tuner() is not right, specially
since there are hybrid devices that have DTV (via DVB API) and
S-Video and/or Composite/RCA capture via V4L2 API.

> 
> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> ---
>  drivers/media/usb/au0828/au0828-video.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/au0828/au0828-video.c b/drivers/media/usb/au0828/au0828-video.c
> index 32bcc56..ed3ba05 100644
> --- a/drivers/media/usb/au0828/au0828-video.c
> +++ b/drivers/media/usb/au0828/au0828-video.c
> @@ -1010,8 +1010,12 @@ static int au0828_v4l2_close(struct file *filp)
>  		goto end;
>  
>  	if (dev->users == 1) {
> -		/* Save some power by putting tuner to sleep */
> -		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
> +		/* Save some power by putting tuner to sleep, if it is free */
> +		/* What happens when radio is using tuner?? */
> +		ret = v4l_enable_media_tuner(vdev);
> +		if (ret == 0)
> +			v4l2_device_call_all(&dev->v4l2_dev, 0, core,
> +					     s_power, 0);
>  		dev->std_set_in_tuner_core = 0;
>  
>  		/* When close the device, set the usb intf0 into alt0 to free
> @@ -1412,10 +1416,16 @@ static int vidioc_s_audio(struct file *file, void *priv, const struct v4l2_audio
>  static int vidioc_g_tuner(struct file *file, void *priv, struct v4l2_tuner *t)
>  {
>  	struct au0828_dev *dev = video_drvdata(file);
> +	struct video_device *vfd = video_devdata(file);
> +	int ret;
>  
>  	if (t->index != 0)
>  		return -EINVAL;
>  
> +	ret = v4l_enable_media_tuner(vfd);
> +	if (ret)
> +		return ret;
> +
>  	dprintk(1, "%s called std_set %d dev_state %d\n", __func__,
>  		dev->std_set_in_tuner_core, dev->dev_state);
>