[PATCH v2 1/1] videobuf2: Add VIDEOBUF2_V4L2 Kconfig option for videobuf2 V4L2 part

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Videobuf2 is now separate from V4L2 and can be now built without it, at
least in principle --- enabling videobuf2 in kernel configuration attempts
to compile videobuf2-v4l2.c but that will fail if CONFIG_VIDEO_V4L2 isn't
enabled.

Solve this by adding a separate Kconfig option for videobuf2-v4l2 and make
it a separate module as well. This means that drivers now need to choose
both the appropriate videobuf2 memory type
(VIDEOBUF2_{VMALLOC,DMA_CONTIG,DMA_SG}) and VIDEOBUF2_V4L2 if they need
both.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
Hi Mauro,

I'm proposing to merge this as it fixes build errors. We can later in
rework the Kconfig options; the rework isn't related to fixing the build
errors in general but rather is a change in the approach used to manage
dependencies. Let's discuss that on #v4l.

since v1:

- Select VIDEOBUF2_V4L2 if both VIDEO_V4L2 and VIDEOBUF2_CORE are
  selected. This way the patch no longer requires changing Kconfig entries
  for effectively all drivers. In certain rare configurations (V4L2 and
  VIDEOBUF2 are enabled but no V4L2 driver uses VIDEOBUF2) VIDEOBUF2_V4L2
  could be enabled without it being needed. This is not really an issue
  though.

 drivers/media/common/videobuf2/Kconfig  | 3 +++
 drivers/media/common/videobuf2/Makefile | 3 ++-
 drivers/media/v4l2-core/Kconfig         | 1 +
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/media/common/videobuf2/Kconfig b/drivers/media/common/videobuf2/Kconfig
index 5df05250de94..17c32ea58395 100644
--- a/drivers/media/common/videobuf2/Kconfig
+++ b/drivers/media/common/videobuf2/Kconfig
@@ -3,6 +3,9 @@ config VIDEOBUF2_CORE
 	select DMA_SHARED_BUFFER
 	tristate
 
+config VIDEOBUF2_V4L2
+	tristate
+
 config VIDEOBUF2_MEMOPS
 	tristate
 	select FRAME_VECTOR
diff --git a/drivers/media/common/videobuf2/Makefile b/drivers/media/common/videobuf2/Makefile
index 19de5ccda20b..7e27bdd44dcc 100644
--- a/drivers/media/common/videobuf2/Makefile
+++ b/drivers/media/common/videobuf2/Makefile
@@ -1,5 +1,6 @@
 
-obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o videobuf2-v4l2.o
+obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
+obj-$(CONFIG_VIDEOBUF2_V4L2) += videobuf2-v4l2.o
 obj-$(CONFIG_VIDEOBUF2_MEMOPS) += videobuf2-memops.o
 obj-$(CONFIG_VIDEOBUF2_VMALLOC) += videobuf2-vmalloc.o
 obj-$(CONFIG_VIDEOBUF2_DMA_CONTIG) += videobuf2-dma-contig.o
diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index bf52fbd07aed..8e37e7c5e0f7 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -7,6 +7,7 @@ config VIDEO_V4L2
 	tristate
 	depends on (I2C || I2C=n) && VIDEO_DEV
 	select RATIONAL
+	select VIDEOBUF2_V4L2 if VIDEOBUF2_CORE
 	default (I2C || I2C=n) && VIDEO_DEV
 
 config VIDEO_ADV_DEBUG
-- 
2.11.0