Re: [PATCH v9 10/15] media: uapi: Add V4L2_CTRL_TYPE_FIXED_POINT
From: Hans Verkuil
Date: Fri Nov 17 2023 - 07:07:55 EST
Here is an RFC patch adding support for 'fraction_bits'. It's lacking
documentation, but it can be used for testing.
It was rather a pain logging fixed point number in a reasonable format,
but I think it is OK.
In userspace (where you can use floating point) it is a lot easier:
printf("%.*g\n", fraction_bits, (double)v * (1.0 / (1ULL << fraction_bits)));
I decided to only expose fraction_bits in struct v4l2_query_ext_ctrl.
I could add it to struct v4l2_queryctrl, but I did not think that was
necessary. Other opinions are welcome.
In the meantime, let me know if this works for your patch series. If it
does, then I can clean this up.
Regards,
Hans
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-ctrls-api.c | 1 +
drivers/media/v4l2-core/v4l2-ctrls-core.c | 72 +++++++++++++++++++----
include/media/v4l2-ctrls.h | 7 ++-
include/uapi/linux/videodev2.h | 20 ++++++-
4 files changed, 85 insertions(+), 15 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
index 002ea6588edf..3132df315b17 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
@@ -1101,6 +1101,7 @@ int v4l2_query_ext_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_query_ext_ctr
qc->elems = ctrl->elems;
qc->nr_of_dims = ctrl->nr_of_dims;
memcpy(qc->dims, ctrl->dims, qc->nr_of_dims * sizeof(qc->dims[0]));
+ qc->fraction_bits = ctrl->fraction_bits;
qc->minimum = ctrl->minimum;
qc->maximum = ctrl->maximum;
qc->default_value = ctrl->default_value;
diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
index a662fb60f73f..0e08a371af5c 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c
@@ -252,12 +252,42 @@ void v4l2_ctrl_type_op_init(const struct v4l2_ctrl *ctrl, u32 from_idx,
}
EXPORT_SYMBOL(v4l2_ctrl_type_op_init);
+static void v4l2_ctrl_log_fp(s64 v, unsigned int fraction_bits)
+{
+ s64 i = v4l2_fp_integer(v, fraction_bits);
+ s64 f = v4l2_fp_fraction(v, fraction_bits);
+
+ if (!f) {
+ pr_cont("%lld", i);
+ } else if (fraction_bits < 20) {
+ u64 div = 1ULL << fraction_bits;
+
+ if (!i && f < 0)
+ pr_cont("-%lld/%llu", -f, div);
+ else if (!i)
+ pr_cont("%lld/%llu", f, div);
+ else if (i < 0 || f < 0)
+ pr_cont("-%lld-%llu/%llu", -i, -f, div);
+ else
+ pr_cont("%lld+%llu/%llu", i, f, div);
+ } else {
+ if (!i && f < 0)
+ pr_cont("-%lld/(2^%u)", -f, fraction_bits);
+ else if (!i)
+ pr_cont("%lld/(2^%u)", f, fraction_bits);
+ else if (i < 0 || f < 0)
+ pr_cont("-%lld-%llu/(2^%u)", -i, -f, fraction_bits);
+ else
+ pr_cont("%lld+%llu/(2^%u)", i, f, fraction_bits);
+ }
+}
+
void v4l2_ctrl_type_op_log(const struct v4l2_ctrl *ctrl)
{
union v4l2_ctrl_ptr ptr = ctrl->p_cur;
if (ctrl->is_array) {
- unsigned i;
+ unsigned int i;
for (i = 0; i < ctrl->nr_of_dims; i++)
pr_cont("[%u]", ctrl->dims[i]);
@@ -266,7 +296,10 @@ void v4l2_ctrl_type_op_log(const struct v4l2_ctrl *ctrl)
switch (ctrl->type) {
case V4L2_CTRL_TYPE_INTEGER:
- pr_cont("%d", *ptr.p_s32);
+ if (!ctrl->fraction_bits)
+ pr_cont("%d", *ptr.p_s32);
+ else
+ v4l2_ctrl_log_fp(*ptr.p_s32, ctrl->fraction_bits);
break;
case V4L2_CTRL_TYPE_BOOLEAN:
pr_cont("%s", *ptr.p_s32 ? "true" : "false");
@@ -281,19 +314,31 @@ void v4l2_ctrl_type_op_log(const struct v4l2_ctrl *ctrl)
pr_cont("0x%08x", *ptr.p_s32);
break;
case V4L2_CTRL_TYPE_INTEGER64:
- pr_cont("%lld", *ptr.p_s64);
+ if (!ctrl->fraction_bits)
+ pr_cont("%lld", *ptr.p_s64);
+ else
+ v4l2_ctrl_log_fp(*ptr.p_s64, ctrl->fraction_bits);
break;
case V4L2_CTRL_TYPE_STRING:
pr_cont("%s", ptr.p_char);
break;
case V4L2_CTRL_TYPE_U8:
- pr_cont("%u", (unsigned)*ptr.p_u8);
+ if (!ctrl->fraction_bits)
+ pr_cont("%u", (unsigned int)*ptr.p_u8);
+ else
+ v4l2_ctrl_log_fp((unsigned int)*ptr.p_u8, ctrl->fraction_bits);
break;
case V4L2_CTRL_TYPE_U16:
- pr_cont("%u", (unsigned)*ptr.p_u16);
+ if (!ctrl->fraction_bits)
+ pr_cont("%u", (unsigned int)*ptr.p_u16);
+ else
+ v4l2_ctrl_log_fp((unsigned int)*ptr.p_u16, ctrl->fraction_bits);
break;
case V4L2_CTRL_TYPE_U32:
- pr_cont("%u", (unsigned)*ptr.p_u32);
+ if (!ctrl->fraction_bits)
+ pr_cont("%u", (unsigned int)*ptr.p_u32);
+ else
+ v4l2_ctrl_log_fp((unsigned int)*ptr.p_u32, ctrl->fraction_bits);
break;
case V4L2_CTRL_TYPE_H264_SPS:
pr_cont("H264_SPS");
@@ -1752,7 +1797,7 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
u32 id, const char *name, enum v4l2_ctrl_type type,
s64 min, s64 max, u64 step, s64 def,
const u32 dims[V4L2_CTRL_MAX_DIMS], u32 elem_size,
- u32 flags, const char * const *qmenu,
+ u32 fraction_bits, u32 flags, const char * const *qmenu,
const s64 *qmenu_int, const union v4l2_ctrl_ptr p_def,
void *priv)
{
@@ -1939,6 +1984,7 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
ctrl->name = name;
ctrl->type = type;
ctrl->flags = flags;
+ ctrl->fraction_bits = fraction_bits;
ctrl->minimum = min;
ctrl->maximum = max;
ctrl->step = step;
@@ -2037,7 +2083,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_custom(struct v4l2_ctrl_handler *hdl,
ctrl = v4l2_ctrl_new(hdl, cfg->ops, cfg->type_ops, cfg->id, name,
type, min, max,
is_menu ? cfg->menu_skip_mask : step, def,
- cfg->dims, cfg->elem_size,
+ cfg->dims, cfg->elem_size, cfg->fraction_bits,
flags, qmenu, qmenu_int, cfg->p_def, priv);
if (ctrl)
ctrl->is_private = cfg->is_private;
@@ -2062,7 +2108,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_std(struct v4l2_ctrl_handler *hdl,
return NULL;
}
return v4l2_ctrl_new(hdl, ops, NULL, id, name, type,
- min, max, step, def, NULL, 0,
+ min, max, step, def, NULL, 0, 0,
flags, NULL, NULL, ptr_null, NULL);
}
EXPORT_SYMBOL(v4l2_ctrl_new_std);
@@ -2095,7 +2141,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
return NULL;
}
return v4l2_ctrl_new(hdl, ops, NULL, id, name, type,
- 0, max, mask, def, NULL, 0,
+ 0, max, mask, def, NULL, 0, 0,
flags, qmenu, qmenu_int, ptr_null, NULL);
}
EXPORT_SYMBOL(v4l2_ctrl_new_std_menu);
@@ -2127,7 +2173,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(struct v4l2_ctrl_handler *hdl,
return NULL;
}
return v4l2_ctrl_new(hdl, ops, NULL, id, name, type,
- 0, max, mask, def, NULL, 0,
+ 0, max, mask, def, NULL, 0, 0,
flags, qmenu, NULL, ptr_null, NULL);
}
@@ -2149,7 +2195,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_std_compound(struct v4l2_ctrl_handler *hdl,
return NULL;
}
return v4l2_ctrl_new(hdl, ops, NULL, id, name, type,
- min, max, step, def, NULL, 0,
+ min, max, step, def, NULL, 0, 0,
flags, NULL, NULL, p_def, NULL);
}
EXPORT_SYMBOL(v4l2_ctrl_new_std_compound);
@@ -2173,7 +2219,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_int_menu(struct v4l2_ctrl_handler *hdl,
return NULL;
}
return v4l2_ctrl_new(hdl, ops, NULL, id, name, type,
- 0, max, 0, def, NULL, 0,
+ 0, max, 0, def, NULL, 0, 0,
flags, NULL, qmenu_int, ptr_null, NULL);
}
EXPORT_SYMBOL(v4l2_ctrl_new_int_menu);
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 59679a42b3e7..c35514c5bf88 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -211,7 +211,8 @@ typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv);
* except for dynamic arrays. In that case it is in the range of
* 1 to @p_array_alloc_elems.
* @dims: The size of each dimension.
- * @nr_of_dims:The number of dimensions in @dims.
+ * @nr_of_dims: The number of dimensions in @dims.
+ * @fraction_bits: The number of fraction bits for fixed point values.
* @menu_skip_mask: The control's skip mask for menu controls. This makes it
* easy to skip menu items that are not valid. If bit X is set,
* then menu item X is skipped. Of course, this only works for
@@ -228,6 +229,7 @@ typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv);
* :math:`ceil(\frac{maximum - minimum}{step}) + 1`.
* Used only if the @type is %V4L2_CTRL_TYPE_INTEGER_MENU.
* @flags: The control's flags.
+ * @fraction_bits: The number of fraction bits for fixed point values.
* @priv: The control's private pointer. For use by the driver. It is
* untouched by the control framework. Note that this pointer is
* not freed when the control is deleted. Should this be needed
@@ -286,6 +288,7 @@ struct v4l2_ctrl {
u32 new_elems;
u32 dims[V4L2_CTRL_MAX_DIMS];
u32 nr_of_dims;
+ u32 fraction_bits;
union {
u64 step;
u64 menu_skip_mask;
@@ -426,6 +429,7 @@ struct v4l2_ctrl_handler {
* @dims: The size of each dimension.
* @elem_size: The size in bytes of the control.
* @flags: The control's flags.
+ * @fraction_bits: The number of fraction bits for fixed point values.
* @menu_skip_mask: The control's skip mask for menu controls. This makes it
* easy to skip menu items that are not valid. If bit X is set,
* then menu item X is skipped. Of course, this only works for
@@ -455,6 +459,7 @@ struct v4l2_ctrl_config {
u32 dims[V4L2_CTRL_MAX_DIMS];
u32 elem_size;
u32 flags;
+ u32 fraction_bits;
u64 menu_skip_mask;
const char * const *qmenu;
const s64 *qmenu_int;
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index c3d4e490ce7c..26ecac19722a 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1944,9 +1944,27 @@ struct v4l2_query_ext_ctrl {
__u32 elems;
__u32 nr_of_dims;
__u32 dims[V4L2_CTRL_MAX_DIMS];
- __u32 reserved[32];
+ __u32 fraction_bits;
+ __u32 reserved[31];
};
+static inline __s64 v4l2_fp_compose(__s64 i, __s64 f, unsigned int fraction_bits)
+{
+ return (i << fraction_bits) + f;
+}
+
+static inline __s64 v4l2_fp_integer(__s64 v, unsigned int fraction_bits)
+{
+ return v / (1LL << fraction_bits);
+}
+
+static inline __s64 v4l2_fp_fraction(__s64 v, unsigned int fraction_bits)
+{
+ __u64 mask = (1ULL << fraction_bits) - 1;
+
+ return v < 0 ? -((-v) & mask) : (v & mask);
+}
+
/* Used in the VIDIOC_QUERYMENU ioctl for querying menu items */
struct v4l2_querymenu {
__u32 id;
--
2.42.0