Re: [PATCH 04/13] x86: use generic swiotlb_ops

Robin Murphy
2018-03-08T16:03:18Z

Hi Christoph,

On 05/03/18 17:46, Christoph Hellwig wrote:
> The generic swiotlb dma ops were based on the x86 ones and provide
> equivalent functionality, so use them.
>
> Also fix the sta2x11 case. For that SOC the dma map ops need an
> additional physical to dma address translations. For swiotlb buffers
> that is done throught the phys_to_dma helper, but the sta2x11_dma_ops
> also added an additional translation on the return value from
> x86_swiotlb_alloc_coherent, which is only correct if that functions
> returns a direct allocation and not a swiotlb buffer. With the
> generic swiotlb and dma-direct code phys_to_dma is not always used
> and the separate sta2x11_dma_ops can be replaced with a simple
> bit that marks if the additional physical to dma address translation
> is needed.

FWIW, last time I looked I got the impression that STA2x11 could just
use dma_pfn_offset - the comments and a2p/p2a logic in sta2x11-fixup.c
certainly imply that the underlying hardware situation is pretty much
exactly that for which dma_pfn_offset exists.

Robin.

>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/x86/include/asm/device.h | 3 +++
> arch/x86/include/asm/swiotlb.h | 8 -------
> arch/x86/kernel/pci-swiotlb.c | 47 +-----------------------------------------
> arch/x86/pci/sta2x11-fixup.c | 46 +++++------------------------------------
> 4 files changed, 9 insertions(+), 95 deletions(-)
>
> diff --git a/arch/x86/include/asm/device.h b/arch/x86/include/asm/device.h
> index 5e12c63b47aa..812bd6c5d602 100644
> --- a/arch/x86/include/asm/device.h
> +++ b/arch/x86/include/asm/device.h
> @@ -6,6 +6,9 @@ struct dev_archdata {
> #if defined(CONFIG_INTEL_IOMMU) || defined(CONFIG_AMD_IOMMU)
> void *iommu; /* hook for IOMMU specific extension */
> #endif
> +#ifdef CONFIG_STA2X11
> + bool is_sta2x11 : 1;
> +#endif
> };
>
> #if defined(CONFIG_X86_DEV_DMA_OPS) && defined(CONFIG_PCI_DOMAINS)
> diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
> index 1c6a6cb230ff..ff6c92eff035 100644
> --- a/arch/x86/include/asm/swiotlb.h
> +++ b/arch/x86/include/asm/swiotlb.h
> @@ -27,12 +27,4 @@ static inline void pci_swiotlb_late_init(void)
> {
> }
> #endif
> -
> -extern void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> - dma_addr_t *dma_handle, gfp_t flags,
> - unsigned long attrs);
> -extern void x86_swiotlb_free_coherent(struct device *dev, size_t size,
> - void *vaddr, dma_addr_t dma_addr,
> - unsigned long attrs);
> -
> #endif /* _ASM_X86_SWIOTLB_H */
> diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
> index bcb6a9bf64ad..661583662430 100644
> --- a/arch/x86/kernel/pci-swiotlb.c
> +++ b/arch/x86/kernel/pci-swiotlb.c
> @@ -17,51 +17,6 @@
>
> int swiotlb __read_mostly;
>
> -void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> - dma_addr_t *dma_handle, gfp_t flags,
> - unsigned long attrs)
> -{
> - void *vaddr;
> -
> - /*
> - * Don't print a warning when the first allocation attempt fails.
> - * swiotlb_alloc_coherent() will print a warning when the DMA
> - * memory allocation ultimately failed.
> - */
> - flags |= __GFP_NOWARN;
> -
> - vaddr = dma_direct_alloc(hwdev, size, dma_handle, flags, attrs);
> - if (vaddr)
> - return vaddr;
> -
> - return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
> -}
> -
> -void x86_swiotlb_free_coherent(struct device *dev, size_t size,
> - void *vaddr, dma_addr_t dma_addr,
> - unsigned long attrs)
> -{
> - if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
> - swiotlb_free_coherent(dev, size, vaddr, dma_addr);
> - else
> - dma_direct_free(dev, size, vaddr, dma_addr, attrs);
> -}
> -
> -static const struct dma_map_ops x86_swiotlb_dma_ops = {
> - .mapping_error = swiotlb_dma_mapping_error,
> - .alloc = x86_swiotlb_alloc_coherent,
> - .free = x86_swiotlb_free_coherent,
> - .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
> - .sync_single_for_device = swiotlb_sync_single_for_device,
> - .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
> - .sync_sg_for_device = swiotlb_sync_sg_for_device,
> - .map_sg = swiotlb_map_sg_attrs,
> - .unmap_sg = swiotlb_unmap_sg_attrs,
> - .map_page = swiotlb_map_page,
> - .unmap_page = swiotlb_unmap_page,
> - .dma_supported = NULL,
> -};
> -
> /*
> * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
> *
> @@ -111,7 +66,7 @@ void __init pci_swiotlb_init(void)
> {
> if (swiotlb) {
> swiotlb_init(0);
> - dma_ops = &x86_swiotlb_dma_ops;
> + dma_ops = &swiotlb_dma_ops;
> }
> }
>
> diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
> index 6c712fe11bdc..eac58e03f43c 100644
> --- a/arch/x86/pci/sta2x11-fixup.c
> +++ b/arch/x86/pci/sta2x11-fixup.c
> @@ -159,43 +159,6 @@ static dma_addr_t a2p(dma_addr_t a, struct pci_dev *pdev)
> return p;
> }
>
> -/**
> - * sta2x11_swiotlb_alloc_coherent - Allocate swiotlb bounce buffers
> - * returns virtual address. This is the only "special" function here.
> - * @dev: PCI device
> - * @size: Size of the buffer
> - * @dma_handle: DMA address
> - * @flags: memory flags
> - */
> -static void *sta2x11_swiotlb_alloc_coherent(struct device *dev,
> - size_t size,
> - dma_addr_t *dma_handle,
> - gfp_t flags,
> - unsigned long attrs)
> -{
> - void *vaddr;
> -
> - vaddr = x86_swiotlb_alloc_coherent(dev, size, dma_handle, flags, attrs);
> - *dma_handle = p2a(*dma_handle, to_pci_dev(dev));
> - return vaddr;
> -}
> -
> -/* We have our own dma_ops: the same as swiotlb but from alloc (above) */
> -static const struct dma_map_ops sta2x11_dma_ops = {
> - .alloc = sta2x11_swiotlb_alloc_coherent,
> - .free = x86_swiotlb_free_coherent,
> - .map_page = swiotlb_map_page,
> - .unmap_page = swiotlb_unmap_page,
> - .map_sg = swiotlb_map_sg_attrs,
> - .unmap_sg = swiotlb_unmap_sg_attrs,
> - .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
> - .sync_single_for_device = swiotlb_sync_single_for_device,
> - .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
> - .sync_sg_for_device = swiotlb_sync_sg_for_device,
> - .mapping_error = swiotlb_dma_mapping_error,
> - .dma_supported = dma_direct_supported,
> -};
> -
> /* At setup time, we use our own ops if the device is a ConneXt one */
> static void sta2x11_setup_pdev(struct pci_dev *pdev)
> {
> @@ -205,7 +168,8 @@ static void sta2x11_setup_pdev(struct pci_dev *pdev)
> return;
> pci_set_consistent_dma_mask(pdev, STA2X11_AMBA_SIZE - 1);
> pci_set_dma_mask(pdev, STA2X11_AMBA_SIZE - 1);
> - pdev->dev.dma_ops = &sta2x11_dma_ops;
> + pdev->dev.dma_ops = &swiotlb_dma_ops;
> + pdev->dev.archdata.is_sta2x11 = true;
>
> /* We must enable all devices as master, for audio DMA to work */
> pci_set_master(pdev);
> @@ -225,7 +189,7 @@ bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
> {
> struct sta2x11_mapping *map;
>
> - if (dev->dma_ops != &sta2x11_dma_ops) {
> + if (!dev->archdata.is_sta2x11) {
> if (!dev->dma_mask)
> return false;
> return addr + size - 1 <= *dev->dma_mask;
> @@ -249,7 +213,7 @@ bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
> */
> dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> {
> - if (dev->dma_ops != &sta2x11_dma_ops)
> + if (!dev->archdata.is_sta2x11)
> return paddr;
> return p2a(paddr, to_pci_dev(dev));
> }
> @@ -261,7 +225,7 @@ dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> */
> phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> {
> - if (dev->dma_ops != &sta2x11_dma_ops)
> + if (!dev->archdata.is_sta2x11)
> return daddr;
> return a2p(daddr, to_pci_dev(dev));
> }
>