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jarkko

Jarkko Sakkinen

Edited 4 days ago
Flattened ioctls:

VCAM_IOC_CREATE
VCAM_IOC_QUERY
VCAM_IOC_SET_FORMAT
VCAM_IOC_ALLOC_FRAMES
VCAM_IOC_IMPORT_DMABUF
VCAM_IOC_QUEUE
VCAM_IOC_DEQUEUE
VCAM_IOC_FREE_FRAMES

The interface is available from fd opened by /dev/vcam, thus making it the life-line of /dev/videoX. The result struct of VCAM_IOC_CREATE provides "control fd", which ATM provides status flag for stream on/off state.

VCAM_IOC_CREATE is one-shot:

1. Before the ioctl is called, other ioctls result -ENOTTY.
2. After successful invocation, the other ioctls become available, and VCAM_IOC_CREATE will result -ENOTTY up until the end.

In other words, no broken use of VIDIOC API and /dev/videoX for outputing frames. Instead, vcam provides a dedicated and consolidated API to perform its task within the constraints what makes sense for virtual webcams and such.

Probably getting ioctls acceptable for reviewers will take a few rounds but I still think that this is the right design choice to get something that we can eventually ship in the mainline kernel.
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jarkko

Jarkko Sakkinen

Reply to @jarkko
It will be reduced a bit. E.g., VCAM_IOC_FREE_FRAMES will be gone.
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