media: add v4l2 JPEG helpers

Add helpers for JPEG header parsing. They allow both scanning for marker segment positions and later parsing the segments individually, as required by s5p-jpeg, as well as parsing all headers in one go, as required by coda-vpu. The frame header is always parsed, as basically all decoders are interested in width, height, and number of components. For convenience, the JPEG chroma subsampling factors are decoded into a v4l2_jpeg_chroma_subsampling enum. Only baseline and extended sequential DCT encoded JPEGs with 8-bit or 12-bit precision with up to four components are supported. Signed-off-by: Philipp Zabel <[email protected]> Signed-off-by: Hans Verkuil <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]>
josf · Apr 14, 2020 · 50733b5 · 50733b5
1 parent dbe9398
commit 50733b5
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diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
@@ -44,6 +44,10 @@ config VIDEO_FIXED_MINOR_RANGES
 config VIDEO_TUNER
 	tristate
 
+# Used by drivers that need v4l2-jpeg.ko
+config V4L2_JPEG_HELPER
+	tristate
+
 # Used by drivers that need v4l2-mem2mem.ko
 config V4L2_MEM2MEM_DEV
 	tristate

diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
@@ -24,6 +24,8 @@ obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 
 obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
 
+obj-$(CONFIG_V4L2_JPEG_HELPER) += v4l2-jpeg.o
+
 obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
 obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
 obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o