Re: [PATCH 1/3] media-ctl: libv4l2subdev: Add DV timings support

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Laurent,

Laurent Pinchart wrote:
> Hi Sakari,
>
> On Tuesday 03 June 2014 15:32:24 Sakari Ailus wrote:
>> On Mon, Jun 02, 2014 at 05:10:02PM +0200, Laurent Pinchart wrote:
>>> Expose the pad-level get caps, query, get and set DV timings ioctls.
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>> ---
>>>
>>>   utils/media-ctl/libv4l2subdev.c | 72 ++++++++++++++++++++++++++++++++++++
>>>   utils/media-ctl/v4l2subdev.h    | 53 ++++++++++++++++++++++++++++++
>>>   2 files changed, 125 insertions(+)
>>>
>>> diff --git a/utils/media-ctl/libv4l2subdev.c
>>> b/utils/media-ctl/libv4l2subdev.c index 14daffa..8015330 100644
>>> --- a/utils/media-ctl/libv4l2subdev.c
>>> +++ b/utils/media-ctl/libv4l2subdev.c
>>> @@ -189,6 +189,78 @@ int v4l2_subdev_set_selection(struct media_entity
>>> *entity,
>>>   	return 0;
>>>   }
>>>
>>> +int v4l2_subdev_get_dv_timings_caps(struct media_entity *entity,
>>> +	struct v4l2_dv_timings_cap *caps)
>>> +{
>>> +	unsigned int pad = caps->pad;
>>> +	int ret;
>>> +
>>> +	ret = v4l2_subdev_open(entity);
>>> +	if (ret < 0)
>>> +		return ret;
>>
>> In every function v4l2_subdev_open() is called before the ioctl command. How
>> about implementing a wrapper which does both, and using that before this
>> patch?
>
> I'm not too fond of the current subdev API. Subdevs are opened implicitly but
> must be closed explicitly. Implicit open is of course easy, but the unbalanced
> API makes me feel uneasy. I'm open to ideas for better alternatives :-)

I had a patch to reference count v4l2_subdev_open() (and close()), but 
it didn't get applied back in 2012. And... apparently the reason for 
that was that it didn't, well, apply. :-)

<URL:http://www.spinics.net/lists/linux-media/msg52258.html>

I'll resend it.

-- 
Sakari Ailus
sakari.ailus@iki.fi