There is still around 18 drivers not yet ported to videobuf2. These driver
don't support freeing buffetrs through REQBUFS(0) hence for these the
memory type probing fails. In order to gain back our previous behaviour in
presence of these, we implement a workaround that assuming MMAP is
supported. Note that an allocator is only created for device with
STREAMING support in the device capabilities. In such case one of MMAP,
USERPTR and DMABUF is required. Though DMABUF came afterward, so is
not an option and in practice none of these drivers will only do USERPTR.
https://bugzilla.gnome.org/show_bug.cgi?id=735660
Also-by: Hans de Goede <hdegoede@redhat.com>
Parenting V4l2Memory to DmabufMemory was in conflict with recent
optimization in DmabufMemory to avoid dup(), and didn't work with
memory sharing. Instead, use a qdata and it's destroy notify.
https://bugzilla.gnome.org/show_bug.cgi?id=730441
All enum that has REQBUFS and CREATE_BUFS where missing S, which was
confusing since they are supposed to match with associcated ioctl name. This
also fixes the yet unused CAN_REQUEST flag check.
Because of the buf in videobuf2, dqbuf may leave the DONE flag being,
which would implied that the buffer is queued. As this has been broken
for 4 years, simply guaranty the state flags integrity when doing
qbuf/dqbuf.
See https://patchwork.linuxtv.org/patch/23641/
This goal of this allocator is mainly to allow tracking the memory.
Currently, when a buffer memory has been modified, the buffer and it's
memory is disposed and lost until the stream is restarted.
