Re: [PATCH v2 5/6] media: uvcvideo: Add support for V4L2_CTRL_TYPE_CTRL_CLASS

From: Ricardo Ribalda Delgado
Date: Fri Mar 12 2021 - 04:58:49 EST

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In reply to: Laurent Pinchart: "Re: [PATCH v2 5/6] media: uvcvideo: Add support for V4L2_CTRL_TYPE_CTRL_CLASS"
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HI Laurent

Thanks for the prompt reply :)

On Fri, Mar 12, 2021 at 2:25 AM Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Thu, Mar 11, 2021 at 11:19:45PM +0100, Ricardo Ribalda wrote:
> > Create all the class controls for the device defined controls.
> >
> > Fixes v4l2-compliance:
> > Control ioctls (Input 0):
> > fail: v4l2-test-controls.cpp(216): missing control class for class 00980000
> > fail: v4l2-test-controls.cpp(216): missing control tclass for class 009a0000
> > test VIDIOC_QUERY_EXT_CTRL/QUERYMENU: FAIL
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> > ---
> > drivers/media/usb/uvc/uvc_ctrl.c | 90 ++++++++++++++++++++++++++++++++
> > drivers/media/usb/uvc/uvcvideo.h | 7 +++
> > 2 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index b3dde98499f4..4e0ed2595ae9 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -357,6 +357,17 @@ static const struct uvc_control_info uvc_ctrls[] = {
> > },
> > };
> >
> > +static const struct uvc_control_class uvc_control_class[] = {
> > + {
> > + .id = V4L2_CID_CAMERA_CLASS,
> > + .name = "Camera Controls",
> > + },
> > + {
> > + .id = V4L2_CID_USER_CLASS,
> > + .name = "User Controls",
> > + },
> > +};
> > +
> > static const struct uvc_menu_info power_line_frequency_controls[] = {
> > { 0, "Disabled" },
> > { 1, "50 Hz" },
> > @@ -1024,6 +1035,49 @@ static int __uvc_ctrl_get(struct uvc_video_chain *chain,
> > return 0;
> > }
> >
> > +static int __uvc_query_v4l2_class(struct uvc_device *dev, u32 req_id,
> > + u32 found_id)
> > +{
> > + bool find_next = req_id & V4L2_CTRL_FLAG_NEXT_CTRL;
> > + int i;
>
> unsigned int as i will never be negative.

Sometimes you are a bit negative with my patches... :)

(sorry, it is Friday)
>
> > +
> > + req_id &= V4L2_CTRL_ID_MASK;
> > +
> > + for (i = 0; i < ARRAY_SIZE(uvc_control_class); i++) {
> > + if (!(dev->ctrl_class_bitmap & BIT(i)))
> > + continue;
> > + if (!find_next) {
> > + if (uvc_control_class[i].id == req_id)
> > + return i;
> > + continue;
> > + }
> > + if ((uvc_control_class[i].id > req_id) &&
> > + (uvc_control_class[i].id < found_id))
>
> No need for the inner parentheses.
>
> > + return i;
> > + }
> > +
> > + return -ENODEV;
> > +}
> > +
> > +static int uvc_query_v4l2_class(struct uvc_device *dev, u32 req_id,
> > + u32 found_id, struct v4l2_queryctrl *v4l2_ctrl)
> > +{
> > + int idx;
> > +
> > + idx = __uvc_query_v4l2_class(dev, req_id, found_id);
> > + if (idx < 0)
> > + return -ENODEV;
> > +
> > + memset(v4l2_ctrl, 0, sizeof(*v4l2_ctrl));
> > + v4l2_ctrl->id = uvc_control_class[idx].id;
> > + strscpy(v4l2_ctrl->name, uvc_control_class[idx].name,
> > + sizeof(v4l2_ctrl->name));
> > + v4l2_ctrl->type = V4L2_CTRL_TYPE_CTRL_CLASS;
> > + v4l2_ctrl->flags = V4L2_CTRL_FLAG_WRITE_ONLY |
> > + V4L2_CTRL_FLAG_READ_ONLY;
>
> v4l2_ctrl->flags = V4L2_CTRL_FLAG_WRITE_ONLY
> | V4L2_CTRL_FLAG_READ_ONLY;
>
> > + return 0;
> > +}
>
> If you agree with the comments below, you could inline
> __uvc_query_v4l2_class() in uvc_query_v4l2_class() as it won't be called
> separately.
>
> > +
> > static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > struct uvc_control *ctrl,
> > struct uvc_control_mapping *mapping,
> > @@ -1123,6 +1177,14 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > struct uvc_control_mapping *mapping;
> > int ret;
> >
> > + /* Check if the ctrl is a know class */
> > + if (!(v4l2_ctrl->id & V4L2_CTRL_FLAG_NEXT_CTRL)) {
> > + ret = uvc_query_v4l2_class(chain->dev, v4l2_ctrl->id,
> > + v4l2_ctrl->id, v4l2_ctrl);
>
> You could pass 0 for found_id here.
>
> > + if (!ret)
> > + return 0;
> > + }
> > +
>
> Should this be done with the chain->ctrl_mutex locked, as
> __uvc_query_v4l2_class() accesses dev->ctrl_class_bitmap that could be
> modified concurrently ?
>
> > ret = mutex_lock_interruptible(&chain->ctrl_mutex);
> > if (ret < 0)
> > return -ERESTARTSYS;
> > @@ -1133,6 +1195,13 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > goto done;
> > }
> >
>
> A comment here along the lines of
>
> /*
> * If we're enumerating control with V4L2_CTRL_FLAG_NEXT_CTRL, check if
> * a class should be inserted between the previous control and the one
> * we have just found.
> */
>
> could be useful, as it's not trivial.

yes, it looks better thanks!

>
> > + if (v4l2_ctrl->id & V4L2_CTRL_FLAG_NEXT_CTRL) {
> > + ret = uvc_query_v4l2_class(chain->dev, v4l2_ctrl->id,
> > + mapping->id, v4l2_ctrl);
> > + if (!ret)
> > + goto done;
> > + }
> > +
> > ret = __uvc_query_v4l2_ctrl(chain, ctrl, mapping, v4l2_ctrl);
> > done:
> > mutex_unlock(&chain->ctrl_mutex);
> > @@ -1422,6 +1491,9 @@ static int uvc_ctrl_add_event(struct v4l2_subscribed_event *sev, unsigned elems)
> > struct uvc_control *ctrl;
> > int ret;
> >
> > + if (__uvc_query_v4l2_class(handle->chain->dev, sev->id, 0) >= 0)
> > + return 0;
>
> Do we really need to succeed ? What's the point in subscribing for
> control change events on a class ? Can't we just check if sev->id is a
> class, and return -EINVAL in that case ?

Unfortunately it is expected that you can subscribe to all the events,
even the ctrl_classes
test VIDIOC_G/S/TRY_EXT_CTRLS: OK
fail: v4l2-test-controls.cpp(835): subscribe event for
control 'User Controls' failed
test VIDIOC_(UN)SUBSCRIBE_EVENT/DQEVENT: FAIL

>
> > +
> > ret = mutex_lock_interruptible(&handle->chain->ctrl_mutex);
> > if (ret < 0)
> > return -ERESTARTSYS;
> > @@ -1458,6 +1530,9 @@ static void uvc_ctrl_del_event(struct v4l2_subscribed_event *sev)
> > {
> > struct uvc_fh *handle = container_of(sev->fh, struct uvc_fh, vfh);
> >
> > + if (__uvc_query_v4l2_class(handle->chain->dev, sev->id, 0) >= 0)
> > + return;
>
> And this could then be dropped, as this function won't be called if the
> subscription failed.
>
> > +
> > mutex_lock(&handle->chain->ctrl_mutex);
> > list_del(&sev->node);
> > mutex_unlock(&handle->chain->ctrl_mutex);
> > @@ -1577,6 +1652,9 @@ int uvc_ctrl_get(struct uvc_video_chain *chain,
> > struct uvc_control *ctrl;
> > struct uvc_control_mapping *mapping;
> >
> > + if (__uvc_query_v4l2_class(chain->dev, xctrl->id, 0) >= 0)
> > + return -EACCES;
> > +
> > ctrl = uvc_find_control(chain, xctrl->id, &mapping);
> > if (ctrl == NULL)
> > return -EINVAL;
> > @@ -1596,6 +1674,9 @@ int uvc_ctrl_set(struct uvc_fh *handle,
> > s32 max;
> > int ret;
> >
> > + if (__uvc_query_v4l2_class(chain->dev, xctrl->id, 0) >= 0)
> > + return -EACCES;
> > +
>
> Similarly as in patch 1/6, should these two checks be moved to
> v4l_s_ctrl() and v4l_s_ext_ctrls(), as it's never valid to get/set a
> class ?

I do not think that it is possible, you need to return -EACCESS if the
control exists and -EINVAL if it does not exist.
v4l_s_ext_ctrls does not know if the ctrl exists.
>
> > ctrl = uvc_find_control(chain, xctrl->id, &mapping);
> > if (ctrl == NULL)
> > return -EINVAL;
> > @@ -2062,6 +2143,7 @@ static int __uvc_ctrl_add_mapping(struct uvc_device *dev,
> > {
> > struct uvc_control_mapping *map;
> > unsigned int size;
> > + int i;
>
> This can be unsigned as i never takes negative values.
I cannot repeat the same joke... even if it is a bad joke
>
> >
> > /* Most mappings come from static kernel data and need to be duplicated.
> > * Mappings that come from userspace will be unnecessarily duplicated,
> > @@ -2085,6 +2167,14 @@ static int __uvc_ctrl_add_mapping(struct uvc_device *dev,
> > if (map->set == NULL)
> > map->set = uvc_set_le_value;
> >
> > + for (i = 0; i < ARRAY_SIZE(uvc_control_class); i++) {
> > + if (V4L2_CTRL_ID2WHICH(uvc_control_class[i].id) ==
> > + V4L2_CTRL_ID2WHICH(map->id)) {
>
> You can write this
>
> if (uvc_control_class[i].id == V4L2_CTRL_ID2WHICH(map->id)) {
>
> as the uvc_control_class array contains control classes only.

Are you sure?
#define V4L2_CID_CAMERA_CLASS (V4L2_CTRL_CLASS_CAMERA | 1)

we are sasing the cid, not the class.

>
> > + dev->ctrl_class_bitmap |= BIT(i);
> > + break;
> > + }
> > + }
> > +
> > list_add_tail(&map->list, &ctrl->info.mappings);
> > uvc_dbg(dev, CONTROL, "Adding mapping '%s' to control %pUl/%u\n",
> > map->name, ctrl->info.entity, ctrl->info.selector);
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index 97df5ecd66c9..63b5d697a438 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -262,6 +262,11 @@ struct uvc_control_mapping {
> > u8 *data);
> > };
> >
> > +struct uvc_control_class {
> > + u32 id;
> > + char name[32];
> > +};
> > +
> > struct uvc_control {
> > struct uvc_entity *entity;
> > struct uvc_control_info info;
> > @@ -707,6 +712,8 @@ struct uvc_device {
> > } async_ctrl;
> >
> > struct uvc_entity *gpio_unit;
> > +
> > + u8 ctrl_class_bitmap;
>
> Should this be stored in the chain, as different chains can have
> different controls ?
>
> > };
> >
> > enum uvc_handle_state {
>
> --
> Regards,
>
> Laurent Pinchart

--
Ricardo Ribalda

Next message: Linus Walleij: "Re: [RFC PATCH 1/5] rpmb: add Replay Protected Memory Block (RPMB) subsystem"
Previous message: Bartosz Golaszewski: "[PATCH v4 10/11] selftests: gpio: add a helper for reading GPIO line names"
In reply to: Laurent Pinchart: "Re: [PATCH v2 5/6] media: uvcvideo: Add support for V4L2_CTRL_TYPE_CTRL_CLASS"
Next in thread: Laurent Pinchart: "Re: [PATCH v2 5/6] media: uvcvideo: Add support for V4L2_CTRL_TYPE_CTRL_CLASS"
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