Am 13.11.21 um 07:22 schrieb Jianqun Xu:
Add DMA_BUF_IOCTL_SYNC_PARTIAL support for user to sync dma-buf with
offset and len.
You have not given an use case for this so it is a bit hard to review.
And from the existing use cases I don't see why this should be necessary.
Even worse from the existing backend implementation I don't even see how
drivers should be able to fulfill this semantics.
Please explain further,
Christian.
Change-Id: I03d2d2e10e48d32aa83c31abade57e0931e1be49
Signed-off-by: Jianqun Xu <jay.xu@xxxxxxxxxxxxxx>
---
drivers/dma-buf/dma-buf.c | 42 ++++++++++++++++++++++++++++++++++++
include/uapi/linux/dma-buf.h | 8 +++++++
2 files changed, 50 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index d9948d58b3f4..78f37f7c3462 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -392,6 +392,7 @@ static long dma_buf_ioctl(struct file *file,
{
struct dma_buf *dmabuf;
struct dma_buf_sync sync;
+ struct dma_buf_sync_partial sync_p;
enum dma_data_direction direction;
int ret;
@@ -430,6 +431,47 @@ static long dma_buf_ioctl(struct file *file,
case DMA_BUF_SET_NAME_B:
return dma_buf_set_name(dmabuf, (const char __user *)arg);
+ case DMA_BUF_IOCTL_SYNC_PARTIAL:
+ if (copy_from_user(&sync_p, (void __user *) arg, sizeof(sync_p)))
+ return -EFAULT;
+
+ if (sync_p.len == 0)
+ return 0;
+
+ if ((sync_p.offset % cache_line_size()) || (sync_p.len % cache_line_size()))
+ return -EINVAL;
+
+ if (sync_p.len > dmabuf->size || sync_p.offset > dmabuf->size - sync_p.len)
+ return -EINVAL;
+
+ if (sync_p.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
+ return -EINVAL;
+
+ switch (sync_p.flags & DMA_BUF_SYNC_RW) {
+ case DMA_BUF_SYNC_READ:
+ direction = DMA_FROM_DEVICE;
+ break;
+ case DMA_BUF_SYNC_WRITE:
+ direction = DMA_TO_DEVICE;
+ break;
+ case DMA_BUF_SYNC_RW:
+ direction = DMA_BIDIRECTIONAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (sync_p.flags & DMA_BUF_SYNC_END)
+ ret = dma_buf_end_cpu_access_partial(dmabuf, direction,
+ sync_p.offset,
+ sync_p.len);
+ else
+ ret = dma_buf_begin_cpu_access_partial(dmabuf, direction,
+ sync_p.offset,
+ sync_p.len);
+
+ return ret;
+
default:
return -ENOTTY;
}
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
index 7f30393b92c3..6236c644624d 100644
--- a/include/uapi/linux/dma-buf.h
+++ b/include/uapi/linux/dma-buf.h
@@ -47,4 +47,12 @@ struct dma_buf_sync {
#define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, u32)
#define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, u64)
+struct dma_buf_sync_partial {
+ __u64 flags;
+ __u32 offset;
+ __u32 len;
+};
+
+#define DMA_BUF_IOCTL_SYNC_PARTIAL _IOW(DMA_BUF_BASE, 2, struct dma_buf_sync_partial)
+
#endif
