v4l2_queryctrl is a subset of v4l2_query_ext_ctrl. If the driver does
not implement v4l2_queryctrl we can implement it with
v4l2_query_ext_ctrl.

Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/v4l2-core/v4l2-dev.c   |  3 ++-
 drivers/media/v4l2-core/v4l2-ioctl.c | 37 +++++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 5bcaeeba4d09..252308a67fa8 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -572,7 +572,8 @@ static void determine_valid_ioctls(struct video_device *vdev)
 	   and that can't be tested here. If the bit for these control ioctls
 	   is set, then the ioctl is valid. But if it is 0, then it can still
 	   be valid if the filehandle passed the control handler. */
-	if (vdev->ctrl_handler || ops->vidioc_queryctrl)
+	if (vdev->ctrl_handler || ops->vidioc_queryctrl ||
+	    ops->vidioc_query_ext_ctrl)
 		__set_bit(_IOC_NR(VIDIOC_QUERYCTRL), valid_ioctls);
 	if (vdev->ctrl_handler || ops->vidioc_query_ext_ctrl)
 		__set_bit(_IOC_NR(VIDIOC_QUERY_EXT_CTRL), valid_ioctls);
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 0304daa8471d..7d615ebc511e 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -2284,9 +2284,11 @@ static int v4l_queryctrl(const struct v4l2_ioctl_ops *ops,
 				struct file *file, void *fh, void *arg)
 {
 	struct video_device *vfd = video_devdata(file);
+	struct v4l2_query_ext_ctrl qec;
 	struct v4l2_queryctrl *p = arg;
 	struct v4l2_fh *vfh =
 		test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
+	int ret;
 
 	if (vfh && vfh->ctrl_handler)
 		return v4l2_queryctrl(vfh->ctrl_handler, p);
@@ -2294,7 +2296,40 @@ static int v4l_queryctrl(const struct v4l2_ioctl_ops *ops,
 		return v4l2_queryctrl(vfd->ctrl_handler, p);
 	if (ops->vidioc_queryctrl)
 		return ops->vidioc_queryctrl(file, fh, p);
-	return -ENOTTY;
+	if (!ops->vidioc_query_ext_ctrl)
+		return -ENOTTY;
+
+	/* Simulate query_ext_ctr using query_ctrl. */
+	qec.id = p->id;
+	ret = ops->vidioc_query_ext_ctrl(file, fh, &qec);
+	if (ret)
+		return ret;
+
+	p->id = qec.id;
+	p->type = qec.type;
+	p->flags = qec.flags;
+	strscpy(p->name, qec.name, sizeof(p->name));
+	switch (p->type) {
+	case V4L2_CTRL_TYPE_INTEGER:
+	case V4L2_CTRL_TYPE_BOOLEAN:
+	case V4L2_CTRL_TYPE_MENU:
+	case V4L2_CTRL_TYPE_INTEGER_MENU:
+	case V4L2_CTRL_TYPE_STRING:
+	case V4L2_CTRL_TYPE_BITMASK:
+		p->minimum = qec.minimum;
+		p->maximum = qec.maximum;
+		p->step = qec.step;
+		p->default_value = qec.default_value;
+		break;
+	default:
+		p->minimum = 0;
+		p->maximum = 0;
+		p->step = 0;
+		p->default_value = 0;
+		break;
+	}
+
+	return 0;
 }
 
 static int v4l_query_ext_ctrl(const struct v4l2_ioctl_ops *ops,

-- 
2.47.0.338.g60cca15819-goog