Commit 7ae2e684 authored by Lukasz Wiecaszek's avatar Lukasz Wiecaszek Committed by Christian König
Browse files

udmabuf: add vmap and vunmap methods to udmabuf_ops 



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: default avatarLukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
Reviewed-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221117171810.75637-1-lukasz.wiecaszek@gmail.com


Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
parent a189b2ee

drivers/dma-buf/udmabuf.c

+28 −0
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ 
#include <linux/slab.h>

#include <linux/udmabuf.h>

#include <linux/hugetlb.h>

#include <linux/vmalloc.h>

#include <linux/iosys-map.h>



static int list_limit = 1024;

module_param(list_limit, int, 0644);
@@ -60,6 +62,30 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) 
	return 0;

}



static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)

{

	struct udmabuf *ubuf = buf->priv;

	void *vaddr;



	dma_resv_assert_held(buf->resv);



	vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);

	if (!vaddr)

		return -EINVAL;



	iosys_map_set_vaddr(map, vaddr);

	return 0;

}



static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)

{

	struct udmabuf *ubuf = buf->priv;



	dma_resv_assert_held(buf->resv);



	vm_unmap_ram(map->vaddr, ubuf->pagecount);

}



static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,

				     enum dma_data_direction direction)

{
@@ -162,6 +188,8 @@ static const struct dma_buf_ops udmabuf_ops = { 
	.unmap_dma_buf	   = unmap_udmabuf,

	.release	   = release_udmabuf,

	.mmap		   = mmap_udmabuf,

	.vmap		   = vmap_udmabuf,

	.vunmap		   = vunmap_udmabuf,

	.begin_cpu_access  = begin_cpu_udmabuf,

	.end_cpu_access    = end_cpu_udmabuf,

};