Hi,
On 11/17/22 07:58, Lukasz Wiecaszek wrote:
The reason behind that patch is associated with videobuf2 subsystem (or more genrally with v4l2 framework) and user created dma buffers (udmabuf). In some circumstances when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem wants to use dma_buf_vmap() method on the attached dma buffer. As udmabuf does not have .vmap operation implemented, such dma_buf_vmap() natually fails.
videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0 videobuf2_common: __buf_prepare: buffer preparation failed: -14
The patch itself seems to be strighforward. It adds implementation of .vmap and .vunmap methods to 'struct dma_buf_ops udmabuf_ops'. .vmap method itself uses vm_map_ram() to map pages linearly into the kernel virtual address space. .vunmap removes mapping created earlier by .vmap. All locking and 'vmapping counting' is done in dma_buf.c so it seems to be redundant/unnecessary in .vmap/.vunmap.
Signed-off-by: Lukasz Wiecaszek lukasz.wiecaszek@gmail.com
If new patch version doesn't contain significant changes and you got acks/reviews for the previous version, then you should add the given acked-by and reviewed-by tags to the commit message by yourself.