Prefer subject capitalization in drivers/pci:
PCI/P2PDMA: Refactor ...
On Sun, Oct 27, 2024 at 04:21:01PM +0200, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch@xxxxxx>
>
> The current scheme with a single helper to determine the P2P status
> and map a scatterlist segment force users to always use the map_sg
> helper to DMA map, which we're trying to get away from because they
> are very cache inefficient.
> ...
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
A couple minor nits below.
> @@ -1412,28 +1411,29 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
> size_t s_length = s->length;
> size_t pad_len = (mask - iova_len + 1) & mask;
>
> - if (is_pci_p2pdma_page(sg_page(s))) {
> - map = pci_p2pdma_map_segment(&p2pdma_state, dev, s);
> - switch (map) {
> - case PCI_P2PDMA_MAP_BUS_ADDR:
> - /*
> - * iommu_map_sg() will skip this segment as
> - * it is marked as a bus address,
> - * __finalise_sg() will copy the dma address
> - * into the output segment.
> - */
> - continue;
> - case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> - /*
> - * Mapping through host bridge should be
> - * mapped with regular IOVAs, thus we
> - * do nothing here and continue below.
> - */
> - break;
> - default:
> - ret = -EREMOTEIO;
> - goto out_restore_sg;
> - }
> + switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(s))) {
> + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> + /*
> + * Mapping through host bridge should be mapped with
> + * regular IOVAs, thus we do nothing here and continue
> + * below.
> + */
I guess this is technically not a fall-through to the next case
because there's no executable code here, but since the comment
separates these two cases, I would find it easier to read if you
included the break here explicitly.
> + case PCI_P2PDMA_MAP_NONE:
> + break;
> +void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
> + struct device *dev, struct page *page);
> +
> +/**
> + * pci_p2pdma_state - check the P2P transfer state of a page
> + * @state: P2P state structure
Checkpatch complains about space before tab here.
> + * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
> + * @state: P2P state structure
And here.
> @@ -462,34 +462,32 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
> enum dma_data_direction dir, unsigned long attrs)
> {
> struct pci_p2pdma_map_state p2pdma_state = {};
> - enum pci_p2pdma_map_type map;
> struct scatterlist *sg;
> int i, ret;
>
> for_each_sg(sgl, sg, nents, i) {
> - if (is_pci_p2pdma_page(sg_page(sg))) {
> - map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
> - switch (map) {
> - case PCI_P2PDMA_MAP_BUS_ADDR:
> - continue;
> - case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> - /*
> - * Any P2P mapping that traverses the PCI
> - * host bridge must be mapped with CPU physical
> - * address and not PCI bus addresses. This is
> - * done with dma_direct_map_page() below.
> - */
> - break;
> - default:
> - ret = -EREMOTEIO;
> + switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(sg))) {
> + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> + /*
> + * Any P2P mapping that traverses the PCI host bridge
> + * must be mapped with CPU physical address and not PCI
> + * bus addresses.
> + */
Same fall-through comment.
> + case PCI_P2PDMA_MAP_NONE:
> + sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
> + sg->offset, sg->length, dir, attrs);
> + if (sg->dma_address == DMA_MAPPING_ERROR) {
> + ret = -EIO;
> goto out_unmap;
> }
> - }
