On Thu, Nov 17, 2022 at 12:04:35PM +0300, Dmitry Osipenko wrote: > 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@xxxxxxxxx> > > 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. > > -- > Best regards, > Dmitry > I would like to thank you all for your patience and on the same time say sorry that I still cannot follow the process (although I have read 'submitting patches' chapter).
