diff options
Diffstat (limited to 'drivers/ntb/ntb_transport.c')
| -rw-r--r-- | drivers/ntb/ntb_transport.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c index 392a5952afd5..a22ea4a4b202 100644 --- a/drivers/ntb/ntb_transport.c +++ b/drivers/ntb/ntb_transport.c @@ -809,16 +809,29 @@ static void ntb_free_mw(struct ntb_transport_ctx *nt, int num_mw) } static int ntb_alloc_mw_buffer(struct ntb_transport_mw *mw, - struct device *dma_dev, size_t align) + struct device *ntb_dev, size_t align) { dma_addr_t dma_addr; void *alloc_addr, *virt_addr; int rc; - alloc_addr = dma_alloc_coherent(dma_dev, mw->alloc_size, - &dma_addr, GFP_KERNEL); + /* + * The buffer here is allocated against the NTB device. The reason to + * use dma_alloc_*() call is to allocate a large IOVA contiguous buffer + * backing the NTB BAR for the remote host to write to. During receive + * processing, the data is being copied out of the receive buffer to + * the kernel skbuff. When a DMA device is being used, dma_map_page() + * is called on the kvaddr of the receive buffer (from dma_alloc_*()) + * and remapped against the DMA device. It appears to be a double + * DMA mapping of buffers, but first is mapped to the NTB device and + * second is to the DMA device. DMA_ATTR_FORCE_CONTIGUOUS is necessary + * in order for the later dma_map_page() to not fail. + */ + alloc_addr = dma_alloc_attrs(ntb_dev, mw->alloc_size, + &dma_addr, GFP_KERNEL, + DMA_ATTR_FORCE_CONTIGUOUS); if (!alloc_addr) { - dev_err(dma_dev, "Unable to alloc MW buff of size %zu\n", + dev_err(ntb_dev, "Unable to alloc MW buff of size %zu\n", mw->alloc_size); return -ENOMEM; } @@ -847,7 +860,7 @@ static int ntb_alloc_mw_buffer(struct ntb_transport_mw *mw, return 0; err: - dma_free_coherent(dma_dev, mw->alloc_size, alloc_addr, dma_addr); + dma_free_coherent(ntb_dev, mw->alloc_size, alloc_addr, dma_addr); return rc; } |