On 08/09/2025 12:13, Laurent Pinchart wrote: > A question for Hans Verkuil below. > > On Thu, Aug 07, 2025 at 09:35:14AM +0200, Ricardo Ribalda wrote: >> On Wed, 16 Jul 2025 at 12:32, Ricardo Ribalda wrote: >>> On Tue, 15 Jul 2025 at 21:35, Laurent Pinchart wrote: >>>> On Mon, Jul 14, 2025 at 05:46:40PM +0200, Ricardo Ribalda wrote: >>>>> On Mon, 14 Jul 2025 at 16:30, Laurent Pinchart wrote: >>>>>> On Tue, Jul 01, 2025 at 01:13:10PM +0200, Ricardo Ribalda wrote: >>>>>>> On Sun, 29 Jun 2025 at 20:13, Laurent Pinchart wrote: >>>>>>>> On Thu, Jun 05, 2025 at 05:53:03PM +0000, Ricardo Ribalda wrote: >>>>>>>>> Virtual entities need to provide more values than get_cur and get_cur >>>>>>>> >>>>>>>> I think you meant "get_info and get_cur". >>>>>>>> >>>>>>>>> for their controls. Add support for get_def, get_min, get_max and >>>>>>>>> get_res. >>>>>>>> >>>>>>>> Do they ? The UVC specification defines controls that don't list >>>>>>>> GET_DEF, GET_MIN, GET_MAX and GET_RES as mandatory requests. Can't we do >>>>>>>> the same for the software controls ? This patch is meant to support the >>>>>>>> UVC_SWENTITY_ORIENTATION and UVC_SWENTITY_ROTATION control in the next >>>>>>>> patch, and those are read-only controls. Aren't GET_INFO and GET_CUR >>>>>>>> enough ? >>>>>>> >>>>>>> V4L2_CID_CAMERA_ROTATION has the type UVC_CTRL_DATA_TYPE_UNSIGNED, >>>>>>> that time requires get_min and get_max. >>>>>> >>>>>> Where does that requirement come from ? Is it because how the >>>>>> corresponding V4L2 type (V4L2_CTRL_TYPE_INTEGER) is handled in >>>>>> uvc_ctrl_clamp() ? uvc_ctrl_clamp() is only called when setting a >>>>>> control, from uvc_ctrl_set(), and V4L2_CID_CAMERA_ROTATION should be >>>>>> read-only. >>>>> >>>>> It its for VIDIOC_QUERY_EXT_CTRL >>>>> >>>>> uvc_query_v4l2_ctrl -> __uvc_query_v4l2_ctrl -> __uvc_queryctrl_boundaries >>>>> >>>>> We need to list the min, max, def and step for every control. They are >>>>> fetched with uvc_ctrl_populate_cache() >>>> >>>> Ah, I see, thanks. >>>> >>>> For GET_RES, I think we can leave it unimplemented. >>>> __uvc_queryctrl_boundaries() will set v4l2_ctrl->step = 0 which seems to >>>> be the right behaviour for a read-only control whose value never >>>> changes. >>> >>> That will break v4l2-compatiblity. Step needs to be != 0 >>> https://git.linuxtv.org/v4l-utils.git/tree/utils/v4l2-compliance/v4l2-test-controls.cpp#n77 >>> >>> Control ioctls (Input 0): >>> fail: v4l2-test-controls.cpp(77): step == 0 >>> fail: v4l2-test-controls.cpp(201): invalid control 009a0923 > > Is that an issue in v4l2-compliance ? For integer controls, > https://docs.kernel.org/userspace-api/media/v4l/vidioc-queryctrl.html#c.V4L.v4l2_ctrl_type > documents the step value as "any". For a read-only control whose value > is constant, do we want to enforce a non-zero value ? If so we should > update the specification. > > Hans, what's your opinion ? The spec is not quite precise enough w.r.t. the step value. Whenever that table says 'any' for the step value, it really should read '>= 1'. It does that already for TYPE_STRING, but it is equally true for INTEGER(64) and U8/16/32. If you create a control using the control framework, then that's actually checked. It's verified by the check_range() function in v4l2-ctrls-core.c. Regards, Hans > > In any case, if GET_RES isn't implemented, we could update > __uvc_queryctrl_boundaries() to set step to 1 instead of 0. That would > fix v4l2-compliance for real controls that don't implement GET_RES. > >>>> As for the minimum and maximum, they are currently set to 0 if the >>>> corresponding operations are not supported. I wonder if we should set >>>> them to the current value instead for read-only controls (as in controls >>>> whose flags report support for GET_CUR only).. >>> >>> I am not sure that I like that approach IMO the code looks worse... >>> but if you prefer that, we can go that way >> >> I am almost ready to send a new version. >> >> What approach do you prefer? > > I particularly like the change in __uvc_queryctrl_boundaries(). That > could probably be done without the rest of the changes though, as > ctrl->uvc_data is already allocated with kzalloc(). > > I also like the fact that the driver can rely on the min/max values to > always be populated in the control data. This could be useful for real > read-only UVC controls. > > Thinking a bit more about this, for read-only controls whose value never > changes, min, max and step are meaningless. V4L2 requires their value to > be set, that's a decision we made in the V4L2 API, but I think a model > where min, max and step would be undefined (or 0) wouldn't be worse. So > maybe it makes sense to handle this in __uvc_queryctrl_boundaries(), > which is where the adaptation between UVC and V4L2 is handled, instead > of storing CUR in the ctrl->uvc_data DEF/MIN/MAX in > uvc_ctrl_populate_cache() ? I think the code could look cleaner. > >>> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > u> > index ec472e111248..47224437018b 100644 >>> --- a/drivers/media/usb/uvc/uvc_ctrl.c >>> +++ b/drivers/media/usb/uvc/uvc_ctrl.c >>> @@ -35,6 +35,8 @@ >>> /* ------------------------------------------------------------------------ >>> * Controls >>> */ >>> +static int __uvc_ctrl_load_cur(struct uvc_video_chain *chain, >>> + struct uvc_control *ctrl); > > I think you can move the function up instead of adding a forward > declaration. > >>> >>> static const struct uvc_control_info uvc_ctrls[] = { >>> { >>> @@ -1272,6 +1274,13 @@ static int uvc_ctrl_populate_cache(struct uvc_video_chain *chain, >>> uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF)); >>> if (ret < 0) >>> return ret; >>> + } else if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR)) { > > A comment (probably at the top of the function) to explain the fallback > would be useful. > >>> + ret = __uvc_ctrl_load_cur(chain, ctrl); >>> + if (!ret) { >>> + memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF), >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), >>> + ctrl->info.size); >>> + } >>> } >>> >>> if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN) { >>> @@ -1279,14 +1288,31 @@ static int uvc_ctrl_populate_cache(struct uvc_video_chain *chain, >>> uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN)); >>> if (ret < 0) >>> return ret; >>> + } else if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR)) { >>> + ret = __uvc_ctrl_load_cur(chain, ctrl); >>> + if (!ret) { >>> + memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN), >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), >>> + ctrl->info.size); >>> + } >>> } >>> + >>> if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) { >>> ret = uvc_ctrl_query_entity(chain->dev, ctrl, UVC_GET_MAX, >>> uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX)); >>> if (ret < 0) >>> return ret; >>> + } else if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR)) { >>> + ret = __uvc_ctrl_load_cur(chain, ctrl); >>> + if (!ret) { >>> + memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX), >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), >>> + ctrl->info.size); >>> + } >>> } >>> + >>> if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES) { >>> + u8 *res; >>> ret = uvc_ctrl_query_entity(chain->dev, ctrl, UVC_GET_RES, >>> uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES)); >>> if (ret < 0) { >>> @@ -1304,7 +1330,13 @@ static int uvc_ctrl_populate_cache(struct uvc_video_chain *chain, >>> "an XU control. Enabling workaround.\n"); >>> memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES), 0, >>> ctrl->info.size); >>> + res = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES); >>> + *res = 1 >>> } >>> + } else { >>> + memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES), 0, ctrl->info.size); >>> + res = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES); >>> + *res = 1; >>> } >>> >>> ctrl->cached = 1; >>> @@ -1541,11 +1573,8 @@ static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain, >>> return ret; >>> } >>> >>> - if (ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF) >>> v4l2_ctrl->default_value = uvc_mapping_get_s32(mapping, >>> UVC_GET_DEF, uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF)); > > You forgot to reduce the indentation here. > >>> - else >>> - v4l2_ctrl->default_value = 0; >>> >>> switch (mapping->v4l2_type) { >>> case V4L2_CTRL_TYPE_MENU: >>> @@ -1576,23 +1605,14 @@ static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain, >>> break; >>> } >>> >>> - if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN) >>> - v4l2_ctrl->minimum = uvc_mapping_get_s32(mapping, UVC_GET_MIN, >>> - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN)); >>> - else >>> - v4l2_ctrl->minimum = 0; >>> + v4l2_ctrl->minimum = uvc_mapping_get_s32(mapping, UVC_GET_MIN, >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN)); >>> >>> - if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) >>> - v4l2_ctrl->maximum = uvc_mapping_get_s32(mapping, UVC_GET_MAX, >>> - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX)); >>> - else >>> - v4l2_ctrl->maximum = 0; >>> + v4l2_ctrl->maximum = uvc_mapping_get_s32(mapping, UVC_GET_MAX, >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX)); >>> >>> - if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES) >>> - v4l2_ctrl->step = uvc_mapping_get_s32(mapping, UVC_GET_RES, >>> - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES)); >>> - else >>> - v4l2_ctrl->step = 0; >>> + v4l2_ctrl->step = uvc_mapping_get_s32(mapping, UVC_GET_RES, >>> + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES)); >>> >>> return 0; >>> } >>> >>>>>>> We can create a new type UVC_CTRL_DATA_TYPE_UNSIGNED_READ_ONLY that >>>>>>> fakes min, max and res, but I think that it is cleaner this approach. >>>>>>> >>>>>>>>> This is a preparation patch. >>>>>>>>> >>>>>>>>> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> >>>>>>>>> --- >>>>>>>>> drivers/media/usb/uvc/uvc_ctrl.c | 12 ++++++++++++ >>>>>>>>> drivers/media/usb/uvc/uvcvideo.h | 8 ++++++++ >>>>>>>>> 2 files changed, 20 insertions(+) >>>>>>>>> >>>>>>>>> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c >>>>>>>>> index 21ec7b978bc7aca21db7cb8fd5d135d876f3330c..59be62ae24a4219fa9d7aacf2ae7382c95362178 100644 >>>>>>>>> --- a/drivers/media/usb/uvc/uvc_ctrl.c >>>>>>>>> +++ b/drivers/media/usb/uvc/uvc_ctrl.c >>>>>>>>> @@ -596,6 +596,18 @@ static int uvc_ctrl_query_entity(struct uvc_device *dev, >>>>>>>>> if (query == UVC_GET_CUR && ctrl->entity->get_cur) >>>>>>>>> return ctrl->entity->get_cur(dev, ctrl->entity, >>>>>>>>> ctrl->info.selector, data, len); >>>>>>>>> + if (query == UVC_GET_DEF && ctrl->entity->get_def) >>>>>>>>> + return ctrl->entity->get_def(dev, ctrl->entity, >>>>>>>>> + ctrl->info.selector, data, len); >>>>>>>>> + if (query == UVC_GET_MIN && ctrl->entity->get_min) >>>>>>>>> + return ctrl->entity->get_min(dev, ctrl->entity, >>>>>>>>> + ctrl->info.selector, data, len); >>>>>>>>> + if (query == UVC_GET_MAX && ctrl->entity->get_max) >>>>>>>>> + return ctrl->entity->get_max(dev, ctrl->entity, >>>>>>>>> + ctrl->info.selector, data, len); >>>>>>>>> + if (query == UVC_GET_RES && ctrl->entity->get_res) >>>>>>>>> + return ctrl->entity->get_res(dev, ctrl->entity, >>>>>>>>> + ctrl->info.selector, data, len); >>>>>>>>> if (query == UVC_GET_INFO && ctrl->entity->get_info) >>>>>>>>> return ctrl->entity->get_info(dev, ctrl->entity, >>>>>>>>> ctrl->info.selector, data); >>>>>>>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h >>>>>>>>> index a931750bdea25b9062dcc7644bf5f2ed89c1cb4c..d6da8ed3ad4cf3377df49923e051fe04d83d2e38 100644 >>>>>>>>> --- a/drivers/media/usb/uvc/uvcvideo.h >>>>>>>>> +++ b/drivers/media/usb/uvc/uvcvideo.h >>>>>>>>> @@ -261,6 +261,14 @@ struct uvc_entity { >>>>>>>>> u8 cs, u8 *caps); >>>>>>>>> int (*get_cur)(struct uvc_device *dev, struct uvc_entity *entity, >>>>>>>>> u8 cs, void *data, u16 size); >>>>>>>>> + int (*get_def)(struct uvc_device *dev, struct uvc_entity *entity, >>>>>>>>> + u8 cs, void *data, u16 size); >>>>>>>>> + int (*get_min)(struct uvc_device *dev, struct uvc_entity *entity, >>>>>>>>> + u8 cs, void *data, u16 size); >>>>>>>>> + int (*get_max)(struct uvc_device *dev, struct uvc_entity *entity, >>>>>>>>> + u8 cs, void *data, u16 size); >>>>>>>>> + int (*get_res)(struct uvc_device *dev, struct uvc_entity *entity, >>>>>>>>> + u8 cs, void *data, u16 size); >>>>>>>>> >>>>>>>>> unsigned int ncontrols; >>>>>>>>> struct uvc_control *controls; >
