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

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Date:	Thu, 28 Jan 2016 12:21:14 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:	tiwai@...e.com, clemens@...isch.de, hans.verkuil@...co.com,
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	johan@...ud.se, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, linux-api@...r.kernel.org,
	alsa-devel@...a-project.org, Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH 17/31] media: au0828 video change to use
 v4l_enable_media_tuner()

On 01/28/2016 08:57 AM, Mauro Carvalho Chehab wrote:
> 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 am not sure if I did or not. I can double check this case.
Do you have concerns that this won't work?

> 
> 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.

How does  v4l-enable_media_source() sound?

thanks,
-- Shuah

> 
>>
>> 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);
>>  


-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@....samsung.com | (970) 217-8978