[media] vb2: add a dev field to use for the default allocation context

The allocation context is nothing more than a per-plane device pointer
to use when allocating buffers. So just provide a dev pointer in vb2_queue
for that purpose and drivers can skip allocating/releasing/filling in
the allocation context unless they require different per-plane device
pointers as used by some Samsung SoCs.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Florian Echtler <floe@butterbrot.org>
Cc: Federico Vaga <federico.vaga@gmail.com>
Cc: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Cc: Scott Jiang <scott.jiang.linux@gmail.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Benoit Parrot <bparrot@ti.com>
Cc: Mikhail Ulyanov <mikhail.ulyanov@cogentembedded.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 444ef3b..d38668c 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -400,6 +400,8 @@
  *		caller. For example, for V4L2, it should match
  *		the V4L2_BUF_TYPE_* in include/uapi/linux/videodev2.h
  * @io_modes:	supported io methods (see vb2_io_modes enum)
+ * @dev:	device to use for the default allocation context if the driver
+ *		doesn't fill in the @alloc_ctx array.
  * @dma_attrs:	DMA attributes to use for the DMA. May be NULL.
  * @fileio_read_once:		report EOF after reading the first buffer
  * @fileio_write_immediately:	queue buffer after each write() call
@@ -467,6 +469,7 @@
 struct vb2_queue {
 	unsigned int			type;
 	unsigned int			io_modes;
+	struct device			*dev;
 	const struct dma_attrs		*dma_attrs;
 	unsigned			fileio_read_once:1;
 	unsigned			fileio_write_immediately:1;