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Message-ID: <3e03ae6c-b586-c314-b015-9b3b5de8fd04@xs4all.nl>
Date: Fri, 12 Mar 2021 11:22:07 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Cc: Ricardo Ribalda <ribalda@...omium.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Tomasz Figa <tfiga@...omium.org>,
linux-media <linux-media@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v2 5/6] media: uvcvideo: Add support for
V4L2_CTRL_TYPE_CTRL_CLASS
On 12/03/2021 11:13, Laurent Pinchart wrote:
> Hi Ricardo,
>
> On Fri, Mar 12, 2021 at 10:57:33AM +0100, Ricardo Ribalda Delgado wrote:
>> On Fri, Mar 12, 2021 at 2:25 AM Laurent Pinchart wrote:
>>> 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@...omium.org>
>>>> ---
>>>> 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
>
> Looks like something that should be dropped from v4l2-compliance,
> there's no use case for subscribing to a class.
It's allowed in the API. You never get an event, since it doesn't change, but
you can subscribe to it. I chose to allow it to avoid exceptions. Basically if
a control never changes, you just never get an event. Whether it is a control
class or a read-only control or a control with just a fixed value, it doesn't
matter for the event control API.
Regards,
Hans
>
>>>> +
>>>> 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.
>
> *sigh* I'm sad that we need this kind of complexity in drivers because
> the API requires us to implement a behaviour that nobody actually cares
> about :-( The way classes are implemented is really a big hack.
>
>>>> 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.
>
> Indeed, my bad.
>
>>>> + 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 {
>
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