Hello, The v4l2_plane data_offset field has been introduced at the same time as the the multiplane API to convey header size information between kernelspace and userspace. The API then became slightly controversial, both because different developers understood the purpose of the field differently (resulting for instance in an out-of-tree driver abusing the field for a different purpose), and because of competing proposals (see for instance "[RFC] Multi format stream support" at http://www.spinics.net/lists/linux-media/msg69130.html). Furthermore, the data_offset field isn't used by any mainline driver except vivid (for testing purpose). I need a different data offset in planes to allow data capture to or data output from a userspace-selected offset within a buffer (mainly for the DMABUF and MMAP memory types). As the data_offset field already has the right name, is unused, and ill-defined, I propose repurposing it. This is what this RFC is about. If the proposal is accepted I'll add another patch to update data_offset usage in the vivid driver. Laurent Pinchart (2): v4l: Repurpose the v4l2_plane data_offset field videobuf2: Repurpose the v4l2_plane data_offset field Documentation/DocBook/media/v4l/io.xml | 19 +++++++------ drivers/media/v4l2-core/videobuf2-core.c | 46 +++++++++++++++++++++++--------- include/media/videobuf2-core.h | 4 +++ include/media/videobuf2-dma-contig.h | 2 +- include/uapi/linux/videodev2.h | 6 +++-- 5 files changed, 54 insertions(+), 23 deletions(-) -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
