staging: vc04_services: Add a V4L2 M2M codec driver

This adds a V4L2 memory to memory device that wraps the MMAL
video decode and video_encode components for H264 and MJPEG encode
and decode, MPEG4, H263, and VP8 decode (and MPEG2 decode
if the appropriate licence has been purchased).

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

drivers/staging/vc04_services/Kconfig

@@ -23,6 +23,7 @@ source "drivers/staging/vc04_services/bcm2835-audio/Kconfig"
 source "drivers/staging/vc04_services/bcm2835-camera/Kconfig"
 source "drivers/staging/vc04_services/vchiq-mmal/Kconfig"
 source "drivers/staging/vc04_services/vc-sm-cma/Kconfig"
+source "drivers/staging/vc04_services/bcm2835-codec/Kconfig"
 
 endif
 

drivers/staging/vc04_services/Makefile

@@ -10,10 +10,11 @@ vchiq-objs := \
    interface/vchiq_arm/vchiq_util.o \
    interface/vchiq_arm/vchiq_connected.o \
 
-obj-$(CONFIG_SND_BCM2835)	+= bcm2835-audio/
-obj-$(CONFIG_VIDEO_BCM2835)	+= bcm2835-camera/
-obj-$(CONFIG_BCM2835_VCHIQ_MMAL) += vchiq-mmal/
-obj-$(CONFIG_BCM_VC_SM_CMA) 	+= vc-sm-cma/
+obj-$(CONFIG_SND_BCM2835)		+= bcm2835-audio/
+obj-$(CONFIG_VIDEO_BCM2835)		+= bcm2835-camera/
+obj-$(CONFIG_BCM2835_VCHIQ_MMAL)	+= vchiq-mmal/
+obj-$(CONFIG_BCM_VC_SM_CMA) 		+= vc-sm-cma/
+obj-$(CONFIG_VIDEO_CODEC_BCM2835)	+= bcm2835-codec/
 
 ccflags-y += -Idrivers/staging/vc04_services -D__VCCOREVER__=0x04000000
 

drivers/staging/vc04_services/bcm2835-codec/Kconfig

@@ -0,0 +1,11 @@
+config VIDEO_CODEC_BCM2835
+	tristate "BCM2835 Video codec support"
+	depends on MEDIA_SUPPORT
+	depends on VIDEO_V4L2 && (ARCH_BCM2835 || COMPILE_TEST)
+	select BCM2835_VCHIQ_MMAL
+	select VIDEOBUF2_DMA_CONTIG
+	select V4L2_MEM2MEM_DEV
+	help
+	  Say Y here to enable the V4L2 video codecs for
+	  Broadcom BCM2835 SoC. This operates over the VCHIQ interface
+	  to a service running on VideoCore.

drivers/staging/vc04_services/bcm2835-codec/Makefile

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+bcm2835-codec-objs := bcm2835-v4l2-codec.o
+
+obj-$(CONFIG_VIDEO_CODEC_BCM2835) += bcm2835-codec.o
+
+ccflags-y += \
+	-Idrivers/staging/vc04_services \
+	-D__VCCOREVER__=0x04000000

drivers/staging/vc04_services/bcm2835-codec/TODO

@@ -0,0 +1,24 @@
+1) Convert to be a platform driver.
+
+Right now when the module probes, it tries to initialize VCHI and
+errors out if it wasn't ready yet.  If bcm2835-v4l2 was built in, then
+VCHI generally isn't ready because it depends on both the firmware and
+mailbox drivers having already loaded.
+
+We should have VCHI create a platform device once it's initialized,
+and have this driver bind to it, so that we automatically load the
+v4l2 module after VCHI loads.
+
+2) Support SELECTION API to define crop region on the image for encode.
+
+Particularly for resolutions that aren't a multiple of the macroblock
+size, the codec will report a resolution that is a multiple of the macroblock
+size (it has to have the memory to decode into), and then a different crop
+region within that buffer.
+The most common example is 1080P, where the buffer will be 1920x1088 with a
+crop region of 1920x1080.
+
+3) Refactor so that the component creation is only on queue_setup, not open.
+
+Fixes v4l2-compliance failure on trying to open 100 instances of the
+device.