The Request API is missing a feature: if userspace did not set any controls, then the request object will not contain a control object (that's created only if the user sets a control in the request). This is fine for e.g. stateless codecs since they require that each request contains controls, so this is always done. And this is also the reason that this hasn't been a problem before, since the Request API is almost exclusively used by stateless codecs. But for e.g. vivid this means that the completed request does not contain any controls in the request containing the control values at the time that the frame was captured (or output). In addition, if a driver needs to set a status control, then that control won't be part of the request either. This RFC series adds a v4l2_ctrl_request_create() function that can be called in the req_validate() callback of the request. If the request doesn't contain a control object, then it will add a new one. This is an RFC for now. Hopefully this will help Yunfei Dong with the development of Read-Only Requests, since that should be a lot simpler with this new function. Also, I am not entirely happy with the name of the function and I also think that we might need a helper in v4l2-common.c that combines with function with vb2_request_validate(), thus avoiding that drivers need to remember to call both v4l2_ctrl_request_create() and vb2_request_validate(). Regards, Hans Hans Verkuil (2): v4l2-ctrls.c: add v4l2_ctrl_request_create vivid: call v4l2_ctrl_request_create() drivers/media/mc/mc-request.c | 3 +- drivers/media/test-drivers/vivid/vivid-core.c | 4 +++ drivers/media/v4l2-core/v4l2-ctrls.c | 35 +++++++++++++++++++ include/media/v4l2-ctrls.h | 16 +++++++++ 4 files changed, 57 insertions(+), 1 deletion(-) -- 2.27.0
