media: media requests: return EBADR instead of EACCES

If requests are used when they shouldn't, or not used when they should,
then return EBADR (Invalid request descriptor) instead of EACCES.

The reason for this change is that EACCES has more to do with permissions
(not being the owner of the resource), but in this case the request file
descriptor is just wrong for the current mode of the device.

Update the documentation accordingly.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: Use wait_queue_head_t for media_request

The portable type for a wait queue is wait_queue_head_t.

Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: EPERM -> EACCES/EBUSY

If requests are not supported by the driver, then return EACCES, not
EPERM.

If you attempt to mix queueing buffers directly and using requests,
then EBUSY is returned instead of EPERM: once a specific queueing mode
has been chosen the queue is 'busy' if you attempt the other mode
(i.e. direct queueing vs via a request).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: add media_request_(un)lock_for_access

Add helper functions to prevent a completed request from being
re-inited while it is being accessed.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: return -EINVAL for invalid request_fds

Instead of returning -ENOENT when a request_fd was not found (VIDIOC_QBUF
and VIDIOC_G/S/TRY_EXT_CTRLS), we now return -EINVAL. This is in line
with what we do when invalid dmabuf fds are passed to e.g. VIDIOC_QBUF.

Also document that EINVAL is returned for invalid m.fd values, we never
documented that.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: add media_request_object_find

Add media_request_object_find to find a request object inside a
request based on ops and priv values.

Objects of the same type (vb2 buffer, control handler) will have
the same ops value. And objects that refer to the same 'parent'
object (e.g. the v4l2_ctrl_handler that has the current driver
state) will have the same priv value.

The caller has to call media_request_object_put() for the returned
object since this function increments the refcount.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: add media_request_get_by_fd

Add media_request_get_by_fd() to find a request based on the file
descriptor.

The caller has to call media_request_put() for the returned
request since this function increments the refcount.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

media: media-request: implement media requests

Add initial media request support:

1) Add MEDIA_IOC_REQUEST_ALLOC ioctl support to media-device.c
2) Add struct media_request to store request objects.
3) Add struct media_request_object to represent a request object.
4) Add MEDIA_REQUEST_IOC_QUEUE/REINIT ioctl support.

Basic lifecycle: the application allocates a request, adds
objects to it, queues the request, polls until it is completed
and can then read the final values of the objects at the time
of completion. When it closes the file descriptor the request
memory will be freed (actually, when the last user of that request
releases the request).

Drivers will bind an object to a request (the 'adds objects to it'
phase), when MEDIA_REQUEST_IOC_QUEUE is called the request is
validated (req_validate op), then queued (the req_queue op).

When done with an object it can either be unbound from the request
(e.g. when the driver has finished with a vb2 buffer) or marked as
completed (e.g. for controls associated with a buffer). When all
objects in the request are completed (or unbound), then the request
fd will signal an exception (poll).

Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Co-developed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Co-developed-by: Alexandre Courbot <acourbot@chromium.org>

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>