On 11/09/2014 12:04 AM, Sakari Ailus wrote:
> The V4L2_SEL_TGT_NATIVE_SIZE target is used to denote e.g. the size of a
> sensor's pixel array.
>
> Signed-off-by: Sakari Ailus <sakari.ai...@iki.fi>
> ---
> Documentation/DocBook/media/v4l/selections-common.xml | 8 ++++++++
> include/uapi/linux/v4l2-common.h | 2 ++
> 2 files changed, 10 insertions(+)
>
> diff --git a/Documentation/DocBook/media/v4l/selections-common.xml
> b/Documentation/DocBook/media/v4l/selections-common.xml
> index 7502f78..5fc833a 100644
> --- a/Documentation/DocBook/media/v4l/selections-common.xml
> +++ b/Documentation/DocBook/media/v4l/selections-common.xml
> @@ -63,6 +63,14 @@
> <entry>Yes</entry>
> </row>
> <row>
> + <entry><constant>V4L2_SEL_TGT_NATIVE_SIZE</constant></entry>
> + <entry>0x0003</entry>
> + <entry>The native size of the device, e.g. a sensor's
> + pixel array.</entry>
You might want to state that top and left are always 0.
> + <entry>Yes</entry>
> + <entry>Yes</entry>
> + </row>
> + <row>
> <entry><constant>V4L2_SEL_TGT_COMPOSE</constant></entry>
> <entry>0x0100</entry>
> <entry>Compose rectangle. Used to configure scaling
> diff --git a/include/uapi/linux/v4l2-common.h
> b/include/uapi/linux/v4l2-common.h
> index 2f6f8ca..1527398 100644
> --- a/include/uapi/linux/v4l2-common.h
> +++ b/include/uapi/linux/v4l2-common.h
> @@ -43,6 +43,8 @@
> #define V4L2_SEL_TGT_CROP_DEFAULT 0x0001
> /* Cropping bounds */
> #define V4L2_SEL_TGT_CROP_BOUNDS 0x0002
> +/* Native frame size */
> +#define V4L2_SEL_TGT_NATIVE_SIZE 0x0003
> /* Current composing area */
> #define V4L2_SEL_TGT_COMPOSE 0x0100
> /* Default composing area */
>
I like this. This would also make it possible to set the 'canvas' size of an
mem2mem device. Currently calling S_FMT for a mem2mem device cannot setup any
scaler since there is no native size. Instead S_FMT effectively *sets* the
native
size. The same is true for webcams with a scaler, which is why you added this in
the first place. Obviously for sensors this target is read-only, but for a
mem2mem
device it can be writable as well.
However, to make full use of this you also need to add input and output
capabilities if the native size can be set:
V4L2_IN_CAP_NATIVE_SIZE
V4L2_OUT_CAP_NATIVE_SIZE
(see ENUMINPUT/ENUMOUTPUT)
This would nicely fill in a hole in the V4L2 Spec.
Regards,
Hans
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