Re: [PATCH v9 10/15] media: uapi: Add V4L2_CTRL_TYPE_FIXED_POINT

From: Hans Verkuil
Date: Wed Nov 15 2023 - 03:22:44 EST


On 10/11/2023 06:48, Shengjiu Wang wrote:
> Fixed point controls are used by the user to configure
> a fixed point value in 64bits, which Q31.32 format.
>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> ---
> .../userspace-api/media/v4l/vidioc-g-ext-ctrls.rst | 13 +++++++------
> .../userspace-api/media/v4l/vidioc-queryctrl.rst | 9 ++++++++-
> .../userspace-api/media/videodev2.h.rst.exceptions | 1 +
> drivers/media/v4l2-core/v4l2-ctrls-api.c | 5 ++++-
> drivers/media/v4l2-core/v4l2-ctrls-core.c | 2 ++
> include/uapi/linux/videodev2.h | 1 +
> 6 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
> index e8475f9fd2cf..e7e5d78dc11e 100644
> --- a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
> +++ b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
> @@ -162,13 +162,13 @@ still cause this situation.
> * - __s32
> - ``value``
> - New value or current value. Valid if this control is not of type
> - ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is
> - not set.
> + ``V4L2_CTRL_TYPE_INTEGER64``, ``V4L2_CTRL_TYPE_FIXED_POINT`` and
> + ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is not set.
> * - __s64
> - ``value64``
> - New value or current value. Valid if this control is of type
> - ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is
> - not set.
> + ``V4L2_CTRL_TYPE_INTEGER64``, ``V4L2_CTRL_TYPE_FIXED_POINT`` and
> + ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is not set.
> * - char *
> - ``string``
> - A pointer to a string. Valid if this control is of type
> @@ -193,8 +193,9 @@ still cause this situation.
> * - __s64 *
> - ``p_s64``
> - A pointer to a matrix control of signed 64-bit values. Valid if
> - this control is of type ``V4L2_CTRL_TYPE_INTEGER64`` and
> - ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set.
> + this control is of type ``V4L2_CTRL_TYPE_INTEGER64``,
> + ``V4L2_CTRL_TYPE_FIXED_POINT`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD``
> + is set.
> * - struct :c:type:`v4l2_area` *
> - ``p_area``
> - A pointer to a struct :c:type:`v4l2_area`. Valid if this control is
> diff --git a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
> index 4d38acafe8e1..f3995ec57044 100644
> --- a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
> +++ b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
> @@ -235,7 +235,8 @@ See also the examples in :ref:`control`.
> - ``default_value``
> - The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_INTEGER64``,
> ``_BOOLEAN``, ``_BITMASK``, ``_MENU``, ``_INTEGER_MENU``, ``_U8``
> - or ``_U16`` control. Not valid for other types of controls.
> + ``_FIXED_POINT`` or ``_U16`` control. Not valid for other types of
> + controls.
>
> .. note::
>
> @@ -549,6 +550,12 @@ See also the examples in :ref:`control`.
> - n/a
> - A struct :c:type:`v4l2_ctrl_av1_film_grain`, containing AV1 Film Grain
> parameters for stateless video decoders.
> + * - ``V4L2_CTRL_TYPE_FIXED_POINT``
> + - any
> + - any
> + - any
> + - A 64-bit integer valued control, containing parameter which is
> + Q31.32 format.
>
> .. raw:: latex
>
> diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> index e61152bb80d1..2faa5a2015eb 100644
> --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> @@ -167,6 +167,7 @@ replace symbol V4L2_CTRL_TYPE_AV1_SEQUENCE :c:type:`v4l2_ctrl_type`
> replace symbol V4L2_CTRL_TYPE_AV1_TILE_GROUP_ENTRY :c:type:`v4l2_ctrl_type`
> replace symbol V4L2_CTRL_TYPE_AV1_FRAME :c:type:`v4l2_ctrl_type`
> replace symbol V4L2_CTRL_TYPE_AV1_FILM_GRAIN :c:type:`v4l2_ctrl_type`
> +replace symbol V4L2_CTRL_TYPE_FIXED_POINT :c:type:`v4l2_ctrl_type`
>
> # V4L2 capability defines
> replace define V4L2_CAP_VIDEO_CAPTURE device-capabilities
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> index 002ea6588edf..e6a0fb8d6791 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> @@ -57,6 +57,7 @@ static int ptr_to_user(struct v4l2_ext_control *c,
> return copy_to_user(c->string, ptr.p_char, len + 1) ?
> -EFAULT : 0;
> case V4L2_CTRL_TYPE_INTEGER64:
> + case V4L2_CTRL_TYPE_FIXED_POINT:n
> c->value64 = *ptr.p_s64;
> break;
> default:
> @@ -132,6 +133,7 @@ static int user_to_new(struct v4l2_ext_control *c, struct v4l2_ctrl *ctrl)
>
> switch (ctrl->type) {
> case V4L2_CTRL_TYPE_INTEGER64:
> + case V4L2_CTRL_TYPE_FIXED_POINT:
> *ctrl->p_new.p_s64 = c->value64;
> break;
> case V4L2_CTRL_TYPE_STRING:
> @@ -540,7 +542,8 @@ static int validate_ctrls(struct v4l2_ext_controls *cs,
> */
> if (ctrl->is_ptr)
> continue;
> - if (ctrl->type == V4L2_CTRL_TYPE_INTEGER64)
> + if (ctrl->type == V4L2_CTRL_TYPE_INTEGER64 ||
> + ctrl->type == V4L2_CTRL_TYPE_FIXED_POINT)
> p_new.p_s64 = &cs->controls[i].value64;
> else
> p_new.p_s32 = &cs->controls[i].value;

You missed a few more: everywhere in this source where V4L2_CTRL_TYPE_INTEGER64
is used you need to add a check for FIXED_POINT as well.

> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
> index a662fb60f73f..9d50df0d9874 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c

Same here for this source.

Note that v4l2_ctrl_type_op_log() needs a separate case for FIXED_POINT so that it
can be logged properly.

> @@ -1187,6 +1187,7 @@ static int std_validate_elem(const struct v4l2_ctrl *ctrl, u32 idx,
> case V4L2_CTRL_TYPE_INTEGER:
> return ROUND_TO_RANGE(ptr.p_s32[idx], u32, ctrl);
> case V4L2_CTRL_TYPE_INTEGER64:
> + case V4L2_CTRL_TYPE_FIXED_POINT:
> /*
> * We can't use the ROUND_TO_RANGE define here due to
> * the u64 divide that needs special care.
> @@ -1779,6 +1780,7 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
> /* Prefill elem_size for all types handled by std_type_ops */
> switch ((u32)type) {
> case V4L2_CTRL_TYPE_INTEGER64:
> + case V4L2_CTRL_TYPE_FIXED_POINT:
> elem_size = sizeof(s64);
> break;
> case V4L2_CTRL_TYPE_STRING:

There is one more place where V4L2_CTRL_TYPE_INTEGER64 is used:
drivers/media/v4l2-core/v4l2-ioctl.c. That should report a fixed point
value in the same way as v4l2_ctrl_type_op_log().

> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index cf8c44595a1d..9482ac66a675 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1903,6 +1903,7 @@ enum v4l2_ctrl_type {
> V4L2_CTRL_TYPE_STRING = 7,
> V4L2_CTRL_TYPE_BITMASK = 8,
> V4L2_CTRL_TYPE_INTEGER_MENU = 9,
> + V4L2_CTRL_TYPE_FIXED_POINT = 10,
>
> /* Compound types are >= 0x0100 */
> V4L2_CTRL_COMPOUND_TYPES = 0x0100,

We will probably need a helper to create a fixed point value from the integer
and fractional part, and one to extract them.

Regards,

Hans