[RFC,04/17] v4l: VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION IOCTLs

Message ID 1324412889-17961-4-git-send-email-sakari.ailus@maxwell.research.nokia.com (mailing list archive)
State RFC, archived
Headers

Commit Message

Sakari Ailus Dec. 20, 2011, 8:27 p.m. UTC
  From: Sakari Ailus <sakari.ailus@iki.fi>

Add support for VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION
IOCTLs. They replace functionality provided by VIDIOC_SUBDEV_S_CROP and
VIDIOC_SUBDEV_G_CROP IOCTLs and also add new functionality (composing).

VIDIOC_SUBDEV_G_CROP and VIDIOC_SUBDEV_S_CROP continue to be supported.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
---
 drivers/media/video/v4l2-subdev.c |   26 ++++++++++++++++++++-
 include/linux/v4l2-subdev.h       |   45 +++++++++++++++++++++++++++++++++++++
 include/media/v4l2-subdev.h       |    5 ++++
 3 files changed, 75 insertions(+), 1 deletions(-)
  

Comments

Laurent Pinchart Jan. 5, 2012, 4:12 p.m. UTC | #1
Hi Sakari,

Thanks for the patch.

On Tuesday 20 December 2011 21:27:56 Sakari Ailus wrote:
> From: Sakari Ailus <sakari.ailus@iki.fi>
> 
> Add support for VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION
> IOCTLs. They replace functionality provided by VIDIOC_SUBDEV_S_CROP and
> VIDIOC_SUBDEV_G_CROP IOCTLs and also add new functionality (composing).
> 
> VIDIOC_SUBDEV_G_CROP and VIDIOC_SUBDEV_S_CROP continue to be supported.

As those ioctls are experimental, should we deprecate them ?

> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
> ---
>  drivers/media/video/v4l2-subdev.c |   26 ++++++++++++++++++++-
>  include/linux/v4l2-subdev.h       |   45 ++++++++++++++++++++++++++++++++++
>  include/media/v4l2-subdev.h       |    5 ++++
>  3 files changed, 75 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/media/video/v4l2-subdev.c
> b/drivers/media/video/v4l2-subdev.c index 65ade5f..e8ae098 100644
> --- a/drivers/media/video/v4l2-subdev.c
> +++ b/drivers/media/video/v4l2-subdev.c
> @@ -36,13 +36,17 @@ static int subdev_fh_init(struct v4l2_subdev_fh *fh,
> struct v4l2_subdev *sd) {
>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
>  	/* Allocate try format and crop in the same memory block */
> -	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop))
> +	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop)
> +			       + sizeof(*fh->try_compose))
>  			      * sd->entity.num_pads, GFP_KERNEL);

Could you check how the 3 structures are aligned on 64-bit platforms ? I'm a 
bit worried about the compiler expecting a 64-bit alignment for one of them, 
and getting only a 32-bit alignment in the end.

What about using kcalloc ?

>  	if (fh->try_fmt == NULL)
>  		return -ENOMEM;
> 
>  	fh->try_crop = (struct v4l2_rect *)
>  		(fh->try_fmt + sd->entity.num_pads);
> +
> +	fh->try_compose = (struct v4l2_rect *)
> +		(fh->try_crop + sd->entity.num_pads);
>  #endif
>  	return 0;
>  }
> @@ -281,6 +285,26 @@ static long subdev_do_ioctl(struct file *file,
> unsigned int cmd, void *arg) return v4l2_subdev_call(sd, pad,
> enum_frame_interval, subdev_fh, fie);
>  	}
> +
> +	case VIDIOC_SUBDEV_G_SELECTION: {
> +		struct v4l2_subdev_selection *sel = arg;

Shouldn't you check sel->which ?

> +		if (sel->pad >= sd->entity.num_pads)
> +			return -EINVAL;
> +
> +		return v4l2_subdev_call(
> +			sd, pad, get_selection, subdev_fh, sel);
> +	}
> +
> +	case VIDIOC_SUBDEV_S_SELECTION: {
> +		struct v4l2_subdev_selection *sel = arg;

And here too ?

> +		if (sel->pad >= sd->entity.num_pads)
> +			return -EINVAL;
> +
> +		return v4l2_subdev_call(
> +			sd, pad, set_selection, subdev_fh, sel);
> +	}
>  #endif
>  	default:
>  		return v4l2_subdev_call(sd, core, ioctl, cmd, arg);
> diff --git a/include/linux/v4l2-subdev.h b/include/linux/v4l2-subdev.h
> index ed29cbb..d53d775 100644
> --- a/include/linux/v4l2-subdev.h
> +++ b/include/linux/v4l2-subdev.h
> @@ -123,6 +123,47 @@ struct v4l2_subdev_frame_interval_enum {
>  	__u32 reserved[9];
>  };
> 
> +#define V4L2_SUBDEV_SEL_FLAG_SIZE_GE			(1 << 0)
> +#define V4L2_SUBDEV_SEL_FLAG_SIZE_LE			(1 << 1)
> +#define V4L2_SUBDEV_SEL_FLAG_KEEP_CONFIG		(1 << 2)
> +
> +/* active cropping area */
> +#define V4L2_SUBDEV_SEL_TGT_CROP_ACTIVE			0
> +/* default cropping area */
> +#define V4L2_SUBDEV_SEL_TGT_CROP_DEFAULT		1
> +/* cropping bounds */
> +#define V4L2_SUBDEV_SEL_TGT_CROP_BOUNDS			2
> +/* current composing area */
> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_ACTIVE		256
> +/* default composing area */
> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_DEFAULT		257
> +/* composing bounds */
> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_BOUNDS		258
> +
> +
> +/**
> + * struct v4l2_subdev_selection - selection info
> + *
> + * @which: either V4L2_SUBDEV_FORMAT_ACTIVE or V4L2_SUBDEV_FORMAT_TRY
> + * @pad: pad number, as reported by the media API
> + * @target: selection target, used to choose one of possible rectangles
> + * @flags: constraints flags
> + * @r: coordinates of selection window
> + * @reserved: for future use, rounds structure size to 64 bytes, set to
> zero + *
> + * Hardware may use multiple helper window to process a video stream.
> + * The structure is used to exchange this selection areas between
> + * an application and a driver.
> + */
> +struct v4l2_subdev_selection {
> +	__u32 which;
> +	__u32 pad;
> +	__u32 target;
> +	__u32 flags;
> +	struct v4l2_rect r;
> +	__u32 reserved[8];
> +};
> +
>  #define VIDIOC_SUBDEV_G_FMT	_IOWR('V',  4, struct v4l2_subdev_format)
>  #define VIDIOC_SUBDEV_S_FMT	_IOWR('V',  5, struct v4l2_subdev_format)
>  #define VIDIOC_SUBDEV_G_FRAME_INTERVAL \
> @@ -137,5 +178,9 @@ struct v4l2_subdev_frame_interval_enum {
>  			_IOWR('V', 75, struct v4l2_subdev_frame_interval_enum)
>  #define VIDIOC_SUBDEV_G_CROP	_IOWR('V', 59, struct v4l2_subdev_crop)
>  #define VIDIOC_SUBDEV_S_CROP	_IOWR('V', 60, struct v4l2_subdev_crop)
> +#define VIDIOC_SUBDEV_G_SELECTION \
> +	_IOWR('V', 61, struct v4l2_subdev_selection)
> +#define VIDIOC_SUBDEV_S_SELECTION \
> +	_IOWR('V', 62, struct v4l2_subdev_selection)
> 
>  #endif
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index f0f3358..26eeaa4 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -466,6 +466,10 @@ struct v4l2_subdev_pad_ops {
>  		       struct v4l2_subdev_crop *crop);
>  	int (*get_crop)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
>  		       struct v4l2_subdev_crop *crop);
> +	int (*get_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
> +			     struct v4l2_subdev_selection *sel);
> +	int (*set_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
> +			     struct v4l2_subdev_selection *sel);
>  };
> 
>  struct v4l2_subdev_ops {
> @@ -551,6 +555,7 @@ struct v4l2_subdev_fh {
>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
>  	struct v4l2_mbus_framefmt *try_fmt;
>  	struct v4l2_rect *try_crop;
> +	struct v4l2_rect *try_compose;
>  #endif
>  };
  
Sakari Ailus Jan. 6, 2012, 11:27 a.m. UTC | #2
Hi Laurent,

Thanks for the comments!

Laurent Pinchart wrote:
> On Tuesday 20 December 2011 21:27:56 Sakari Ailus wrote:
>> From: Sakari Ailus <sakari.ailus@iki.fi>
>>
>> Add support for VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION
>> IOCTLs. They replace functionality provided by VIDIOC_SUBDEV_S_CROP and
>> VIDIOC_SUBDEV_G_CROP IOCTLs and also add new functionality (composing).
>>
>> VIDIOC_SUBDEV_G_CROP and VIDIOC_SUBDEV_S_CROP continue to be supported.
> 
> As those ioctls are experimental, should we deprecate them ?

I'm also in favour of doing that. But I'll make it a separate patch.

>> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
>> ---
>>  drivers/media/video/v4l2-subdev.c |   26 ++++++++++++++++++++-
>>  include/linux/v4l2-subdev.h       |   45 ++++++++++++++++++++++++++++++++++
>>  include/media/v4l2-subdev.h       |    5 ++++
>>  3 files changed, 75 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/media/video/v4l2-subdev.c
>> b/drivers/media/video/v4l2-subdev.c index 65ade5f..e8ae098 100644
>> --- a/drivers/media/video/v4l2-subdev.c
>> +++ b/drivers/media/video/v4l2-subdev.c
>> @@ -36,13 +36,17 @@ static int subdev_fh_init(struct v4l2_subdev_fh *fh,
>> struct v4l2_subdev *sd) {
>>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
>>  	/* Allocate try format and crop in the same memory block */
>> -	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop))
>> +	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop)
>> +			       + sizeof(*fh->try_compose))
>>  			      * sd->entity.num_pads, GFP_KERNEL);
> 
> Could you check how the 3 structures are aligned on 64-bit platforms ? I'm a 
> bit worried about the compiler expecting a 64-bit alignment for one of them, 
> and getting only a 32-bit alignment in the end.
> 
> What about using kcalloc ?

kcalloc won't make a difference --- see the implementation. Do you think
this is really an issue in practice?

If we want to ensure alignment I'd just allocate them separately. Or
create a struct out of them locally, and get the pointers from that
struct --- then the alignment would be the same as if those were part of
a single struct. That achieves the desired result and also keeps error
handling trivial.

I wouldn't want to start relying on the alignment based on the sizes of
these structures.

>>  	if (fh->try_fmt == NULL)
>>  		return -ENOMEM;
>>
>>  	fh->try_crop = (struct v4l2_rect *)
>>  		(fh->try_fmt + sd->entity.num_pads);
>> +
>> +	fh->try_compose = (struct v4l2_rect *)
>> +		(fh->try_crop + sd->entity.num_pads);
>>  #endif
>>  	return 0;
>>  }
>> @@ -281,6 +285,26 @@ static long subdev_do_ioctl(struct file *file,
>> unsigned int cmd, void *arg) return v4l2_subdev_call(sd, pad,
>> enum_frame_interval, subdev_fh, fie);
>>  	}
>> +
>> +	case VIDIOC_SUBDEV_G_SELECTION: {
>> +		struct v4l2_subdev_selection *sel = arg;
> 
> Shouldn't you check sel->which ?

Yes.

>> +		if (sel->pad >= sd->entity.num_pads)
>> +			return -EINVAL;
>> +
>> +		return v4l2_subdev_call(
>> +			sd, pad, get_selection, subdev_fh, sel);
>> +	}
>> +
>> +	case VIDIOC_SUBDEV_S_SELECTION: {
>> +		struct v4l2_subdev_selection *sel = arg;
> 
> And here too ?

Yes.

>> +		if (sel->pad >= sd->entity.num_pads)
>> +			return -EINVAL;
>> +
>> +		return v4l2_subdev_call(
>> +			sd, pad, set_selection, subdev_fh, sel);
>> +	}
>>  #endif
>>  	default:
>>  		return v4l2_subdev_call(sd, core, ioctl, cmd, arg);
>> diff --git a/include/linux/v4l2-subdev.h b/include/linux/v4l2-subdev.h
>> index ed29cbb..d53d775 100644
>> --- a/include/linux/v4l2-subdev.h
>> +++ b/include/linux/v4l2-subdev.h
>> @@ -123,6 +123,47 @@ struct v4l2_subdev_frame_interval_enum {
>>  	__u32 reserved[9];
>>  };
>>
>> +#define V4L2_SUBDEV_SEL_FLAG_SIZE_GE			(1 << 0)
>> +#define V4L2_SUBDEV_SEL_FLAG_SIZE_LE			(1 << 1)
>> +#define V4L2_SUBDEV_SEL_FLAG_KEEP_CONFIG		(1 << 2)
>> +
>> +/* active cropping area */
>> +#define V4L2_SUBDEV_SEL_TGT_CROP_ACTIVE			0
>> +/* default cropping area */
>> +#define V4L2_SUBDEV_SEL_TGT_CROP_DEFAULT		1
>> +/* cropping bounds */
>> +#define V4L2_SUBDEV_SEL_TGT_CROP_BOUNDS			2
>> +/* current composing area */
>> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_ACTIVE		256
>> +/* default composing area */
>> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_DEFAULT		257
>> +/* composing bounds */
>> +#define V4L2_SUBDEV_SEL_TGT_COMPOSE_BOUNDS		258
>> +
>> +
>> +/**
>> + * struct v4l2_subdev_selection - selection info
>> + *
>> + * @which: either V4L2_SUBDEV_FORMAT_ACTIVE or V4L2_SUBDEV_FORMAT_TRY
>> + * @pad: pad number, as reported by the media API
>> + * @target: selection target, used to choose one of possible rectangles
>> + * @flags: constraints flags
>> + * @r: coordinates of selection window
>> + * @reserved: for future use, rounds structure size to 64 bytes, set to
>> zero + *
>> + * Hardware may use multiple helper window to process a video stream.
>> + * The structure is used to exchange this selection areas between
>> + * an application and a driver.
>> + */
>> +struct v4l2_subdev_selection {
>> +	__u32 which;
>> +	__u32 pad;
>> +	__u32 target;
>> +	__u32 flags;
>> +	struct v4l2_rect r;
>> +	__u32 reserved[8];
>> +};
>> +
>>  #define VIDIOC_SUBDEV_G_FMT	_IOWR('V',  4, struct v4l2_subdev_format)
>>  #define VIDIOC_SUBDEV_S_FMT	_IOWR('V',  5, struct v4l2_subdev_format)
>>  #define VIDIOC_SUBDEV_G_FRAME_INTERVAL \
>> @@ -137,5 +178,9 @@ struct v4l2_subdev_frame_interval_enum {
>>  			_IOWR('V', 75, struct v4l2_subdev_frame_interval_enum)
>>  #define VIDIOC_SUBDEV_G_CROP	_IOWR('V', 59, struct v4l2_subdev_crop)
>>  #define VIDIOC_SUBDEV_S_CROP	_IOWR('V', 60, struct v4l2_subdev_crop)
>> +#define VIDIOC_SUBDEV_G_SELECTION \
>> +	_IOWR('V', 61, struct v4l2_subdev_selection)
>> +#define VIDIOC_SUBDEV_S_SELECTION \
>> +	_IOWR('V', 62, struct v4l2_subdev_selection)
>>
>>  #endif
>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>> index f0f3358..26eeaa4 100644
>> --- a/include/media/v4l2-subdev.h
>> +++ b/include/media/v4l2-subdev.h
>> @@ -466,6 +466,10 @@ struct v4l2_subdev_pad_ops {
>>  		       struct v4l2_subdev_crop *crop);
>>  	int (*get_crop)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
>>  		       struct v4l2_subdev_crop *crop);
>> +	int (*get_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
>> +			     struct v4l2_subdev_selection *sel);
>> +	int (*set_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
>> +			     struct v4l2_subdev_selection *sel);
>>  };
>>
>>  struct v4l2_subdev_ops {
>> @@ -551,6 +555,7 @@ struct v4l2_subdev_fh {
>>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
>>  	struct v4l2_mbus_framefmt *try_fmt;
>>  	struct v4l2_rect *try_crop;
>> +	struct v4l2_rect *try_compose;
>>  #endif
>>  };
>
  
Laurent Pinchart Jan. 6, 2012, noon UTC | #3
Hi Sakari,

On Friday 06 January 2012 12:27:03 Sakari Ailus wrote:
> Laurent Pinchart wrote:
> > On Tuesday 20 December 2011 21:27:56 Sakari Ailus wrote:
> >> From: Sakari Ailus <sakari.ailus@iki.fi>
> >> 
> >> Add support for VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION
> >> IOCTLs. They replace functionality provided by VIDIOC_SUBDEV_S_CROP and
> >> VIDIOC_SUBDEV_G_CROP IOCTLs and also add new functionality (composing).
> >> 
> >> VIDIOC_SUBDEV_G_CROP and VIDIOC_SUBDEV_S_CROP continue to be supported.
> > 
> > As those ioctls are experimental, should we deprecate them ?
> 
> I'm also in favour of doing that. But I'll make it a separate patch.
> 
> >> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
> >> ---
> >> 
> >>  drivers/media/video/v4l2-subdev.c |   26 ++++++++++++++++++++-
> >>  include/linux/v4l2-subdev.h       |   45
> >>  ++++++++++++++++++++++++++++++++++ include/media/v4l2-subdev.h       |
> >>     5 ++++
> >>  3 files changed, 75 insertions(+), 1 deletions(-)
> >> 
> >> diff --git a/drivers/media/video/v4l2-subdev.c
> >> b/drivers/media/video/v4l2-subdev.c index 65ade5f..e8ae098 100644
> >> --- a/drivers/media/video/v4l2-subdev.c
> >> +++ b/drivers/media/video/v4l2-subdev.c
> >> @@ -36,13 +36,17 @@ static int subdev_fh_init(struct v4l2_subdev_fh *fh,
> >> struct v4l2_subdev *sd) {
> >> 
> >>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
> >>  
> >>  	/* Allocate try format and crop in the same memory block */
> >> 
> >> -	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop))
> >> +	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop)
> >> +			       + sizeof(*fh->try_compose))
> >> 
> >>  			      * sd->entity.num_pads, GFP_KERNEL);
> > 
> > Could you check how the 3 structures are aligned on 64-bit platforms ?
> > I'm a bit worried about the compiler expecting a 64-bit alignment for
> > one of them, and getting only a 32-bit alignment in the end.
> > 
> > What about using kcalloc ?
> 
> kcalloc won't make a difference --- see the implementation. Do you think
> this is really an issue in practice?

It won't make a difference for the alignment, it's just that we allocate an 
array, so kcalloc seemed right.

> If we want to ensure alignment I'd just allocate them separately. Or
> create a struct out of them locally, and get the pointers from that
> struct --- then the alignment would be the same as if those were part of
> a single struct. That achieves the desired result and also keeps error
> handling trivial.
>
> I wouldn't want to start relying on the alignment based on the sizes of
> these structures.

Sounds good to me. Allocating them as part of a bigger structure internally 
could be more efficient than separate allocations, but I'm fine with both.
  
Sakari Ailus Jan. 7, 2012, 9:09 a.m. UTC | #4
Hi Laurent,

Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Friday 06 January 2012 12:27:03 Sakari Ailus wrote:
>> Laurent Pinchart wrote:
>>> On Tuesday 20 December 2011 21:27:56 Sakari Ailus wrote:
>>>> From: Sakari Ailus <sakari.ailus@iki.fi>
>>>>
>>>> Add support for VIDIOC_SUBDEV_S_SELECTION and VIDIOC_SUBDEV_G_SELECTION
>>>> IOCTLs. They replace functionality provided by VIDIOC_SUBDEV_S_CROP and
>>>> VIDIOC_SUBDEV_G_CROP IOCTLs and also add new functionality (composing).
>>>>
>>>> VIDIOC_SUBDEV_G_CROP and VIDIOC_SUBDEV_S_CROP continue to be supported.
>>>
>>> As those ioctls are experimental, should we deprecate them ?
>>
>> I'm also in favour of doing that. But I'll make it a separate patch.
>>
>>>> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
>>>> ---
>>>>
>>>>  drivers/media/video/v4l2-subdev.c |   26 ++++++++++++++++++++-
>>>>  include/linux/v4l2-subdev.h       |   45
>>>>  ++++++++++++++++++++++++++++++++++ include/media/v4l2-subdev.h       |
>>>>     5 ++++
>>>>  3 files changed, 75 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/drivers/media/video/v4l2-subdev.c
>>>> b/drivers/media/video/v4l2-subdev.c index 65ade5f..e8ae098 100644
>>>> --- a/drivers/media/video/v4l2-subdev.c
>>>> +++ b/drivers/media/video/v4l2-subdev.c
>>>> @@ -36,13 +36,17 @@ static int subdev_fh_init(struct v4l2_subdev_fh *fh,
>>>> struct v4l2_subdev *sd) {
>>>>
>>>>  #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
>>>>  
>>>>  	/* Allocate try format and crop in the same memory block */
>>>>
>>>> -	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop))
>>>> +	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop)
>>>> +			       + sizeof(*fh->try_compose))
>>>>
>>>>  			      * sd->entity.num_pads, GFP_KERNEL);
>>>
>>> Could you check how the 3 structures are aligned on 64-bit platforms ?
>>> I'm a bit worried about the compiler expecting a 64-bit alignment for
>>> one of them, and getting only a 32-bit alignment in the end.
>>>
>>> What about using kcalloc ?
>>
>> kcalloc won't make a difference --- see the implementation. Do you think
>> this is really an issue in practice?
> 
> It won't make a difference for the alignment, it's just that we allocate an 
> array, so kcalloc seemed right.
> 
>> If we want to ensure alignment I'd just allocate them separately. Or
>> create a struct out of them locally, and get the pointers from that
>> struct --- then the alignment would be the same as if those were part of
>> a single struct. That achieves the desired result and also keeps error
>> handling trivial.
>>
>> I wouldn't want to start relying on the alignment based on the sizes of
>> these structures.
> 
> Sounds good to me. Allocating them as part of a bigger structure internally 
> could be more efficient than separate allocations, but I'm fine with both.

On second thought, I think I'll combine them into a new anonymous struct
the field name of which I call "pad", unless that requires too intrusive
changes in other drivers. How about that?
  
Sakari Ailus Jan. 7, 2012, 11:09 a.m. UTC | #5
Sakari Ailus wrote:
...
> On second thought, I think I'll combine them into a new anonymous struct
> the field name of which I call "pad", unless that requires too intrusive
> changes in other drivers. How about that?

And the answer to that is "no". The smia++ driver does store the format,
crop and compose values in arrays indexed by pad numbers which I think
is a natural thing for the driver to do. In many functiona the driver
uses internally it's trivial to choose the array either from driver's
internal data structure (V4L2_SUBDEV_FORMAT_ACTIVE) or the file handle
(V4L2_SUBDEV_FORMAT_TRY).

Alternatively a named struct could be created for the same, but the
drivers might not need all the fields at all, or choose to store them in
a different form.
  
Laurent Pinchart Jan. 7, 2012, 3:54 p.m. UTC | #6
Hi Sakari,

On Saturday 07 January 2012 12:09:29 Sakari Ailus wrote:
> Sakari Ailus wrote:
> ...
> 
> > On second thought, I think I'll combine them into a new anonymous struct
> > the field name of which I call "pad", unless that requires too intrusive
> > changes in other drivers. How about that?
> 
> And the answer to that is "no". The smia++ driver does store the format,
> crop and compose values in arrays indexed by pad numbers which I think
> is a natural thing for the driver to do. In many functiona the driver
> uses internally it's trivial to choose the array either from driver's
> internal data structure (V4L2_SUBDEV_FORMAT_ACTIVE) or the file handle
> (V4L2_SUBDEV_FORMAT_TRY).
> 
> Alternatively a named struct could be created for the same, but the
> drivers might not need all the fields at all, or choose to store them in
> a different form.

Drivers should use the v4l2_subdev_get_try_format(), 
v4l2_subdev_get_try_crop() and v4l2_subdev_get_try_compose() functions to 
access TRY formats and selection rectangles on file handles, so they shouldn't 
care about the allocation details.
  
Sakari Ailus Jan. 7, 2012, 4:53 p.m. UTC | #7
Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Saturday 07 January 2012 12:09:29 Sakari Ailus wrote:
>> Sakari Ailus wrote:
>> ...
>>
>>> On second thought, I think I'll combine them into a new anonymous struct
>>> the field name of which I call "pad", unless that requires too intrusive
>>> changes in other drivers. How about that?
>>
>> And the answer to that is "no". The smia++ driver does store the format,
>> crop and compose values in arrays indexed by pad numbers which I think
>> is a natural thing for the driver to do. In many functiona the driver
>> uses internally it's trivial to choose the array either from driver's
>> internal data structure (V4L2_SUBDEV_FORMAT_ACTIVE) or the file handle
>> (V4L2_SUBDEV_FORMAT_TRY).
>>
>> Alternatively a named struct could be created for the same, but the
>> drivers might not need all the fields at all, or choose to store them in
>> a different form.
> 
> Drivers should use the v4l2_subdev_get_try_format(), 
> v4l2_subdev_get_try_crop() and v4l2_subdev_get_try_compose() functions to 
> access TRY formats and selection rectangles on file handles, so they shouldn't 
> care about the allocation details.

Good point... That requires some changes as well, like introduction of
v4l2_subdev_get_try_compose(). :-)
  

Patch

diff --git a/drivers/media/video/v4l2-subdev.c b/drivers/media/video/v4l2-subdev.c
index 65ade5f..e8ae098 100644
--- a/drivers/media/video/v4l2-subdev.c
+++ b/drivers/media/video/v4l2-subdev.c
@@ -36,13 +36,17 @@  static int subdev_fh_init(struct v4l2_subdev_fh *fh, struct v4l2_subdev *sd)
 {
 #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
 	/* Allocate try format and crop in the same memory block */
-	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop))
+	fh->try_fmt = kzalloc((sizeof(*fh->try_fmt) + sizeof(*fh->try_crop)
+			       + sizeof(*fh->try_compose))
 			      * sd->entity.num_pads, GFP_KERNEL);
 	if (fh->try_fmt == NULL)
 		return -ENOMEM;
 
 	fh->try_crop = (struct v4l2_rect *)
 		(fh->try_fmt + sd->entity.num_pads);
+
+	fh->try_compose = (struct v4l2_rect *)
+		(fh->try_crop + sd->entity.num_pads);
 #endif
 	return 0;
 }
@@ -281,6 +285,26 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 		return v4l2_subdev_call(sd, pad, enum_frame_interval, subdev_fh,
 					fie);
 	}
+
+	case VIDIOC_SUBDEV_G_SELECTION: {
+		struct v4l2_subdev_selection *sel = arg;
+
+		if (sel->pad >= sd->entity.num_pads)
+			return -EINVAL;
+
+		return v4l2_subdev_call(
+			sd, pad, get_selection, subdev_fh, sel);
+	}
+
+	case VIDIOC_SUBDEV_S_SELECTION: {
+		struct v4l2_subdev_selection *sel = arg;
+
+		if (sel->pad >= sd->entity.num_pads)
+			return -EINVAL;
+
+		return v4l2_subdev_call(
+			sd, pad, set_selection, subdev_fh, sel);
+	}
 #endif
 	default:
 		return v4l2_subdev_call(sd, core, ioctl, cmd, arg);
diff --git a/include/linux/v4l2-subdev.h b/include/linux/v4l2-subdev.h
index ed29cbb..d53d775 100644
--- a/include/linux/v4l2-subdev.h
+++ b/include/linux/v4l2-subdev.h
@@ -123,6 +123,47 @@  struct v4l2_subdev_frame_interval_enum {
 	__u32 reserved[9];
 };
 
+#define V4L2_SUBDEV_SEL_FLAG_SIZE_GE			(1 << 0)
+#define V4L2_SUBDEV_SEL_FLAG_SIZE_LE			(1 << 1)
+#define V4L2_SUBDEV_SEL_FLAG_KEEP_CONFIG		(1 << 2)
+
+/* active cropping area */
+#define V4L2_SUBDEV_SEL_TGT_CROP_ACTIVE			0
+/* default cropping area */
+#define V4L2_SUBDEV_SEL_TGT_CROP_DEFAULT		1
+/* cropping bounds */
+#define V4L2_SUBDEV_SEL_TGT_CROP_BOUNDS			2
+/* current composing area */
+#define V4L2_SUBDEV_SEL_TGT_COMPOSE_ACTIVE		256
+/* default composing area */
+#define V4L2_SUBDEV_SEL_TGT_COMPOSE_DEFAULT		257
+/* composing bounds */
+#define V4L2_SUBDEV_SEL_TGT_COMPOSE_BOUNDS		258
+
+
+/**
+ * struct v4l2_subdev_selection - selection info
+ *
+ * @which: either V4L2_SUBDEV_FORMAT_ACTIVE or V4L2_SUBDEV_FORMAT_TRY
+ * @pad: pad number, as reported by the media API
+ * @target: selection target, used to choose one of possible rectangles
+ * @flags: constraints flags
+ * @r: coordinates of selection window
+ * @reserved: for future use, rounds structure size to 64 bytes, set to zero
+ *
+ * Hardware may use multiple helper window to process a video stream.
+ * The structure is used to exchange this selection areas between
+ * an application and a driver.
+ */
+struct v4l2_subdev_selection {
+	__u32 which;
+	__u32 pad;
+	__u32 target;
+	__u32 flags;
+	struct v4l2_rect r;
+	__u32 reserved[8];
+};
+
 #define VIDIOC_SUBDEV_G_FMT	_IOWR('V',  4, struct v4l2_subdev_format)
 #define VIDIOC_SUBDEV_S_FMT	_IOWR('V',  5, struct v4l2_subdev_format)
 #define VIDIOC_SUBDEV_G_FRAME_INTERVAL \
@@ -137,5 +178,9 @@  struct v4l2_subdev_frame_interval_enum {
 			_IOWR('V', 75, struct v4l2_subdev_frame_interval_enum)
 #define VIDIOC_SUBDEV_G_CROP	_IOWR('V', 59, struct v4l2_subdev_crop)
 #define VIDIOC_SUBDEV_S_CROP	_IOWR('V', 60, struct v4l2_subdev_crop)
+#define VIDIOC_SUBDEV_G_SELECTION \
+	_IOWR('V', 61, struct v4l2_subdev_selection)
+#define VIDIOC_SUBDEV_S_SELECTION \
+	_IOWR('V', 62, struct v4l2_subdev_selection)
 
 #endif
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index f0f3358..26eeaa4 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -466,6 +466,10 @@  struct v4l2_subdev_pad_ops {
 		       struct v4l2_subdev_crop *crop);
 	int (*get_crop)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
 		       struct v4l2_subdev_crop *crop);
+	int (*get_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
+			     struct v4l2_subdev_selection *sel);
+	int (*set_selection)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
+			     struct v4l2_subdev_selection *sel);
 };
 
 struct v4l2_subdev_ops {
@@ -551,6 +555,7 @@  struct v4l2_subdev_fh {
 #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
 	struct v4l2_mbus_framefmt *try_fmt;
 	struct v4l2_rect *try_crop;
+	struct v4l2_rect *try_compose;
 #endif
 };