On Thu, Jul 24, 2025 at 10:03:13AM +0200, Christoph Hellwig wrote:
On Wed, Jul 23, 2025 at 04:00:06PM +0300, Leon Romanovsky wrote:
From: Leon Romanovsky leonro@nvidia.com
Export the pci_p2pdma_map_type() function to allow external modules and subsystems to determine the appropriate mapping type for P2PDMA transfers between a provider and target device.
External modules have no business doing this.
So what's the plan?
Today the new DMA API broadly has the pattern:
switch (pci_p2pdma_state(p2pdma_state, dev, page)) { [..] if (dma_use_iova(state)) { ret = dma_iova_link(dev, state, paddr, offset, [..] } else { dma_addr = dma_map_page(dev, page, 0, map->dma_entry_size, [..]
You can't fully use the new API flow without calling pci_p2pdma_state(), which is also not exported today.
Is the idea the full new DMA API flow should not be available to modules? We did export dma_iova_link().
Otherwise, the p2p step needs two functions - a struct page-full and a struct page-less version, and they need to be exported.
The names here are not so good, it would be nicer to have them be a dma_* prefixed function since they are used with the other dma_ functions.
Jason