[PATCHv3 8/8] videobuf2: handle non-contiguous DMA allocations

Sergey Senozhatsky
2021-07-09T09:21:03Z

This adds support for new noncontiguous DMA API, which
requires allocators to have two execution branches: one
for the current API, and one for the new one.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Christoph Hellwig <hch@lst.de>
---
.../common/videobuf2/videobuf2-dma-contig.c | 139 ++++++++++++++----
1 file changed, 114 insertions(+), 25 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
index 1e218bc440c6..7408ac9ed60a 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
@@ -17,6 +17,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
+#include <linux/highmem.h>

#include <media/videobuf2-v4l2.h>
#include <media/videobuf2-dma-contig.h>
@@ -42,6 +43,7 @@ struct vb2_dc_buf {
struct dma_buf_attachment *db_attach;

struct vb2_buffer *vb;
+ bool coherent_mem;
};

/*********************************************/
@@ -78,14 +80,22 @@ static void *vb2_dc_cookie(struct vb2_buffer *vb, void *buf_priv)
static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
{
struct vb2_dc_buf *buf = buf_priv;
- struct dma_buf_map map;
- int ret;

- if (!buf->vaddr && buf->db_attach) {
- ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
- buf->vaddr = ret ? NULL : map.vaddr;
+ if (buf->vaddr)
+ return buf->vaddr;
+
+ if (buf->db_attach) {
+ struct dma_buf_map map;
+
+ if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
+ buf->vaddr = map.vaddr;
+
+ return buf->vaddr;
}

+ if (!buf->coherent_mem)
+ buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size,
+ buf->dma_sgt);
return buf->vaddr;
}

@@ -101,13 +111,26 @@ static void vb2_dc_prepare(void *buf_priv)
struct vb2_dc_buf *buf = buf_priv;
struct sg_table *sgt = buf->dma_sgt;

+ /* This takes care of DMABUF and user-enforced cache sync hint */
if (buf->vb->skip_cache_sync_on_prepare)
return;

+ /*
+ * Coherent MMAP buffers do not need to be synced, unlike USERPTR
+ * and non-coherent MMAP buffers.
+ */
+ if (buf->vb->memory == V4L2_MEMORY_MMAP && buf->coherent_mem)
+ return;
+
if (!sgt)
return;

+ /* For both USERPTR and non-coherent MMAP */
dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
+
+ /* Non-coherent MMAP only */
+ if (!buf->coherent_mem && buf->vaddr)
+ flush_kernel_vmap_range(buf->vaddr, buf->size);
}

static void vb2_dc_finish(void *buf_priv)
@@ -115,13 +138,26 @@ static void vb2_dc_finish(void *buf_priv)
struct vb2_dc_buf *buf = buf_priv;
struct sg_table *sgt = buf->dma_sgt;

+ /* This takes care of DMABUF and user-enforced cache sync hint */
if (buf->vb->skip_cache_sync_on_finish)
return;

+ /*
+ * Coherent MMAP buffers do not need to be synced, unlike USERPTR
+ * and non-coherent MMAP buffers.
+ */
+ if (buf->vb->memory == V4L2_MEMORY_MMAP && buf->coherent_mem)
+ return;
+
if (!sgt)
return;

+ /* For both USERPTR and non-coherent MMAP */
dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
+
+ /* Non-coherent MMAP only */
+ if (!buf->coherent_mem && buf->vaddr)
+ invalidate_kernel_vmap_range(buf->vaddr, buf->size);
}

/*********************************************/
@@ -139,17 +175,63 @@ static void vb2_dc_put(void *buf_priv)
sg_free_table(buf->sgt_base);
kfree(buf->sgt_base);
}
- dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
- buf->attrs);
+
+ if (buf->coherent_mem) {
+ dma_free_attrs(buf->dev, buf->size, buf->cookie,
+ buf->dma_addr, buf->attrs);
+ } else {
+ if (buf->vaddr)
+ dma_vunmap_noncontiguous(buf->dev, buf->vaddr);
+ dma_free_noncontiguous(buf->dev, buf->size,
+ buf->dma_sgt, buf->dma_addr);
+ }
put_device(buf->dev);
kfree(buf);
}

+static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf)
+{
+ struct vb2_queue *q = buf->vb->vb2_queue;
+
+ buf->cookie = dma_alloc_attrs(buf->dev,
+ buf->size,
+ &buf->dma_addr,
+ GFP_KERNEL | q->gfp_flags,
+ buf->attrs);
+ if (!buf->cookie)
+ return -ENOMEM;
+
+ if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
+ return 0;
+
+ buf->vaddr = buf->cookie;
+ return 0;
+}
+
+static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf)
+{
+ struct vb2_queue *q = buf->vb->vb2_queue;
+
+ buf->dma_sgt = dma_alloc_noncontiguous(buf->dev,
+ buf->size,
+ buf->dma_dir,
+ GFP_KERNEL | q->gfp_flags,
+ buf->attrs);
+ if (!buf->dma_sgt)
+ return -ENOMEM;
+ /*
+ * For requests that need kernel mapping (DMA_ATTR_NO_KERNEL_MAPPING
+ * bit is cleared) we perform dma_vmap_noncontiguous() in vb2_dc_vadd().
+ */
+ return 0;
+}
+
static void *vb2_dc_alloc(struct vb2_buffer *vb,
struct device *dev,
unsigned long size)
{
struct vb2_dc_buf *buf;
+ int ret;

if (WARN_ON(!dev))
return ERR_PTR(-EINVAL);
@@ -159,27 +241,28 @@ static void *vb2_dc_alloc(struct vb2_buffer *vb,
return ERR_PTR(-ENOMEM);

buf->attrs = vb->vb2_queue->dma_attrs;
- buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
- GFP_KERNEL | vb->vb2_queue->gfp_flags,
- buf->attrs);
- if (!buf->cookie) {
- dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
- kfree(buf);
- return ERR_PTR(-ENOMEM);
- }
-
- if ((buf->attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0)
- buf->vaddr = buf->cookie;
+ buf->dma_dir = vb->vb2_queue->dma_dir;
+ buf->vb = vb;
+ buf->coherent_mem = vb->vb2_queue->coherent_mem;

+ buf->size = size;
/* Prevent the device from being released while the buffer is used */
buf->dev = get_device(dev);
- buf->size = size;
- buf->dma_dir = vb->vb2_queue->dma_dir;
+
+ if (buf->coherent_mem)
+ ret = vb2_dc_alloc_coherent(buf);
+ else
+ ret = vb2_dc_alloc_non_coherent(buf);
+
+ if (ret) {
+ dev_err(dev, "dma alloc of size %ld failed\n", size);
+ kfree(buf);
+ return ERR_PTR(-ENOMEM);
+ }

buf->handler.refcount = &buf->refcount;
buf->handler.put = vb2_dc_put;
buf->handler.arg = buf;
- buf->vb = vb;

refcount_set(&buf->refcount, 1);

@@ -196,9 +279,12 @@ static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
return -EINVAL;
}

- ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
- buf->dma_addr, buf->size, buf->attrs);
-
+ if (buf->coherent_mem)
+ ret = dma_mmap_attrs(buf->dev, vma, buf->cookie, buf->dma_addr,
+ buf->size, buf->attrs);
+ else
+ ret = dma_mmap_noncontiguous(buf->dev, vma, buf->size,
+ buf->dma_sgt);
if (ret) {
pr_err("Remapping memory failed, error: %d\n", ret);
return ret;
@@ -362,7 +448,7 @@ static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct dma_buf_map *map)
{
struct vb2_dc_buf *buf = dbuf->priv;

- dma_buf_map_set_vaddr(map, buf->vaddr);
+ dma_buf_map_set_vaddr(map, vb2_dc_vaddr(buf->vb, buf));

return 0;
}
@@ -390,6 +476,9 @@ static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
int ret;
struct sg_table *sgt;

+ if (!buf->coherent_mem)
+ return buf->dma_sgt;
+
sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
if (!sgt) {
dev_err(buf->dev, "failed to alloc sg table\n");
--
2.32.0.93.g670b81a890-goog