From: Guangming Cao Guangming.Cao@mediatek.com

On Tue, 2021-08-31 at 14:47 +0200, Daniel Vetter wrote:

On Mon, Aug 30, 2021 at 10:39:11AM +0800, guangming.cao@mediatek.com wrote:

...

From: Guangming Cao Guangming.Cao@mediatek.com

When mapping the memory represented by a dma-buf into a device's address space, it might be desireable to map the memory with certain DMA attributes. Thus, introduce the dma_mapping_attrs field in the dma_buf_attachment structure so that when the memory is mapped with dma_buf_map_attachment, it is mapped with the desired DMA attributes.

Signed-off-by: Isaac J. Manjarres isaacm@codeaurora.org Signed-off-by: Sandeep Patil sspatil@google.com Signed-off-by: Guangming Cao Guangming.Cao@mediatek.com

Can you pls include the code that's going to use this here too?

At a glance all the attributes you might want to set are supposed to be under the control of the exporter, not the importer. -Daniel

Hi Daniel,

Sorry for the late. Currently I couldn't upload the coding going to use this part because of some miscellaneous reasons.

Just as I said in commit message, for dma_heap, users can't skip cache sync or other opetrations when map iova[dma_buf_map_attachment] by fill (struct dma_buf_attachment).dma_map_attrs, it's not dma_map_attrs expected(link: https://github.com/torvalds/linux/blob/master/Documentation/core-api/dma-att... ).

Correspondingly, if they use dma_buf to map iova[dma_buf_map_attrs], they will not meet this issue. So, I think it's a design flaw for dma_heap.

BRs! Guangming

...

---

drivers/dma-buf/heaps/cma_heap.c | 6 ++++-- drivers/dma-buf/heaps/system_heap.c | 6 ++++-- include/linux/dma-buf.h | 3 +++ 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma- buf/heaps/cma_heap.c index 0c05b79870f9..2c9feb3bfc3e 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -99,9 +99,10 @@ static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachme { struct dma_heap_attachment *a = attachment->priv; struct sg_table *table = &a->table;

• int attrs = attachment->dma_map_attrs; int ret;

• ret = dma_map_sgtable(attachment->dev, table, direction, 0);

• ret = dma_map_sgtable(attachment->dev, table, direction,

attrs); if (ret) return ERR_PTR(-ENOMEM); a->mapped = true; @@ -113,9 +114,10 @@ static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction) { struct dma_heap_attachment *a = attachment->priv;

• int attrs = attachment->dma_map_attrs;

  a->mapped = false;

• dma_unmap_sgtable(attachment->dev, table, direction, 0);

• dma_unmap_sgtable(attachment->dev, table, direction, attrs);

}

static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma- buf/heaps/system_heap.c index 23a7e74ef966..fc7b1e02988e 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -130,9 +130,10 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac { struct dma_heap_attachment *a = attachment->priv; struct sg_table *table = a->table;

• int attrs = attachment->dma_map_attrs; int ret;

• ret = dma_map_sgtable(attachment->dev, table, direction, 0);

• ret = dma_map_sgtable(attachment->dev, table, direction,

attrs); if (ret) return ERR_PTR(ret);

@@ -145,9 +146,10 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction) { struct dma_heap_attachment *a = attachment->priv;

• int attrs = attachment->dma_map_attrs;

  a->mapped = false;

• dma_unmap_sgtable(attachment->dev, table, direction, 0);

• dma_unmap_sgtable(attachment->dev, table, direction, attrs);

}

static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index efdc56b9d95f..4d650731766e 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -379,6 +379,8 @@ struct dma_buf_attach_ops {

• @importer_ops: importer operations for this attachment, if

provided

• dma_buf_map/unmap_attachment() must be called with the dma_resv

lock held.

• @importer_priv: importer specific attachment data.

• • @dma_map_attrs: DMA attributes to be used when the exporter

maps the buffer

• • through dma_buf_map_attachment.
  • This structure holds the attachment information between the

dma_buf buffer

• and its user device(s). The list contains one attachment struct

per device @@ -399,6 +401,7 @@ struct dma_buf_attachment { const struct dma_buf_attach_ops *importer_ops; void *importer_priv; void *priv;

• unsigned long dma_map_attrs;

};

/**

2.17.1