On 06/09/2024 00:53, Laurent Pinchart wrote: > Companding refers to compression and expansion of pixel data to fit in a > smaller range. The control is named V4L2_CID_COMPANDING, and only > supports compression initially. > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > --- > Changes since v1: > > - Rename V4L2_COMPANDING_ALAW to V4L2_COMPANDING_COMPRESS > - Document V4L2_COMPANDING_LINEAR and V4L2_COMPANDING_COMPRESS > --- > .../media/v4l/ext-ctrls-image-process.rst | 16 ++++++++++++++++ > drivers/media/v4l2-core/v4l2-ctrls-defs.c | 9 +++++++++ > include/uapi/linux/v4l2-controls.h | 5 +++++ > 3 files changed, 30 insertions(+) > > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > index b1c2ab2854af..d529b0a8cd41 100644 > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst > @@ -55,3 +55,19 @@ Image Process Control IDs > control value divided by e.g. 0x100, meaning that to get no > digital gain the control value needs to be 0x100. The no-gain > configuration is also typically the default. > + > +``V4L2_CID_COMPANDING (menu)`` > + Companding refers to compression and expansion of pixel data to fit in a > + smaller range. > + > + > +.. tabularcolumns:: |p{5.7cm}|p{11.8cm}| > + > +.. flat-table:: > + :header-rows: 0 > + :stub-columns: 0 > + > + * - ``V4L2_COMPANDING_LINEAR`` > + - No companding. > + * - ``V4L2_COMPANDING_COMPRESS`` It's weird that this is called 'COMPRESS', > + - Compress the data using a device-specific curve. > diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c > index 1ea52011247a..841e415a88ae 100644 > --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c > +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c > @@ -611,6 +611,11 @@ const char * const *v4l2_ctrl_get_menu(u32 id) > "Cyclic", > NULL, > }; > + static const char * const companding[] = { > + "Linear", > + "A-Law", but it is called 'A-Law' here. I think the same name should be used for both as this is confusing. Regards, Hans > + NULL > + }; > > switch (id) { > case V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ: > @@ -750,6 +755,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id) > return camera_orientation; > case V4L2_CID_MPEG_VIDEO_INTRA_REFRESH_PERIOD_TYPE: > return intra_refresh_period_type; > + case V4L2_CID_COMPANDING: > + return companding; > default: > return NULL; > } > @@ -1164,6 +1171,7 @@ const char *v4l2_ctrl_get_name(u32 id) > case V4L2_CID_TEST_PATTERN: return "Test Pattern"; > case V4L2_CID_DEINTERLACING_MODE: return "Deinterlacing Mode"; > case V4L2_CID_DIGITAL_GAIN: return "Digital Gain"; > + case V4L2_CID_COMPANDING: return "Companding"; > > /* DV controls */ > /* Keep the order of the 'case's the same as in v4l2-controls.h! */ > @@ -1421,6 +1429,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type, > case V4L2_CID_CAMERA_ORIENTATION: > case V4L2_CID_MPEG_VIDEO_INTRA_REFRESH_PERIOD_TYPE: > case V4L2_CID_HDR_SENSOR_MODE: > + case V4L2_CID_COMPANDING: > *type = V4L2_CTRL_TYPE_MENU; > break; > case V4L2_CID_LINK_FREQ: > diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h > index 974fd254e573..ca9e25f72886 100644 > --- a/include/uapi/linux/v4l2-controls.h > +++ b/include/uapi/linux/v4l2-controls.h > @@ -1225,6 +1225,11 @@ enum v4l2_jpeg_chroma_subsampling { > #define V4L2_CID_TEST_PATTERN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 3) > #define V4L2_CID_DEINTERLACING_MODE (V4L2_CID_IMAGE_PROC_CLASS_BASE + 4) > #define V4L2_CID_DIGITAL_GAIN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 5) > +#define V4L2_CID_COMPANDING (V4L2_CID_IMAGE_PROC_CLASS_BASE + 6) > +enum v4l2_companding { > + V4L2_COMPANDING_LINEAR = 0, > + V4L2_COMPANDING_COMPRESS = 1, > +}; > > /* DV-class control IDs defined by V4L2 */ > #define V4L2_CID_DV_CLASS_BASE (V4L2_CTRL_CLASS_DV | 0x900)