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Message-ID: <20100308165500.GB4568@phenom.dumpdata.com>
Date: Mon, 8 Mar 2010 11:55:00 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Albert Herranz <albert_herranz@...oo.es>
Cc: linux-usb@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, x86@...nel.org,
linux-ia64@...r.kernel.org
Subject: Re: [LKML] [RFC PATCH v3 04/11] swiotlb: support
NOT_COHERENT_CACHE PowerPC platforms
On Sun, Mar 07, 2010 at 01:11:45PM +0100, Albert Herranz wrote:
> The current SWIOTLB code does not support NOT_COHERENT_CACHE platforms.
> This patch adds support for NOT_COHERENT_CACHE platforms to SWIOTLB by
> adding two platform specific functions swiotlb_dma_sync_page() and
> swiotlb_dma_sync() which can be used to explicitly manage cache coherency.
Hey Albert,
I've been doing some posting in this area to split the physical / bus
address translation so that multiple platforms can utilize it. I was
wondering if it makes sense to utilize some of those concepts (ie, extend it
for DMA coherency) for your code:
https://lists.linux-foundation.org/pipermail/iommu/2010-February/002066.html
And here is the git tree that goes on top of those patches:
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb-2.6.git xen-swiotlb-0.5
>
> On PowerPC these functions are mapped to their corresponding
> __dma_sync_page() and __dma_sync() functions.
> On other architectures using SWIOTLB these functions are optimized out.
>
> This will be used later to support SWIOTLB on the Nintendo Wii video game
> console.
>
> Signed-off-by: Albert Herranz <albert_herranz@...oo.es>
> CC: linuxppc-dev@...ts.ozlabs.org
> CC: linux-kernel@...r.kernel.org
> CC: x86@...nel.org
> CC: linux-ia64@...r.kernel.org
> ---
> arch/ia64/include/asm/swiotlb.h | 10 ++++++++++
> arch/powerpc/include/asm/swiotlb.h | 3 +++
> arch/x86/include/asm/swiotlb.h | 10 ++++++++++
> lib/swiotlb.c | 30 ++++++++++++++++++++++++------
> 4 files changed, 47 insertions(+), 6 deletions(-)
>
> diff --git a/arch/ia64/include/asm/swiotlb.h b/arch/ia64/include/asm/swiotlb.h
> index f0acde6..6722090 100644
> --- a/arch/ia64/include/asm/swiotlb.h
> +++ b/arch/ia64/include/asm/swiotlb.h
> @@ -14,4 +14,14 @@ static inline void pci_swiotlb_init(void)
> }
> #endif
>
> +static inline void swiotlb_dma_sync_page(struct page *page,
> + unsigned long offset,
> + size_t size, int direction)
> +{
> +}
> +
> +static inline void swiotlb_dma_sync(void *vaddr, size_t size, int direction)
> +{
> +}
> +
> #endif /* ASM_IA64__SWIOTLB_H */
> diff --git a/arch/powerpc/include/asm/swiotlb.h b/arch/powerpc/include/asm/swiotlb.h
> index 8979d4c..603b343 100644
> --- a/arch/powerpc/include/asm/swiotlb.h
> +++ b/arch/powerpc/include/asm/swiotlb.h
> @@ -22,4 +22,7 @@ int __init swiotlb_setup_bus_notifier(void);
>
> extern void pci_dma_dev_setup_swiotlb(struct pci_dev *pdev);
>
> +#define swiotlb_dma_sync_page __dma_sync_page
> +#define swiotlb_dma_sync __dma_sync
> +
> #endif /* __ASM_SWIOTLB_H */
> diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
> index 8085277..e5f6d9c 100644
> --- a/arch/x86/include/asm/swiotlb.h
> +++ b/arch/x86/include/asm/swiotlb.h
> @@ -20,4 +20,14 @@ static inline void pci_swiotlb_init(void)
>
> static inline void dma_mark_clean(void *addr, size_t size) {}
>
> +static inline void swiotlb_dma_sync_page(struct page *page,
> + unsigned long offset,
> + size_t size, int direction)
> +{
> +}
> +
> +static inline void swiotlb_dma_sync(void *vaddr, size_t size, int direction)
> +{
> +}
> +
> #endif /* _ASM_X86_SWIOTLB_H */
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 94db5df..8f2dad9 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -346,10 +346,13 @@ static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
> local_irq_save(flags);
> buffer = kmap_atomic(pfn_to_page(pfn),
> KM_BOUNCE_READ);
> - if (dir == DMA_TO_DEVICE)
> + if (dir == DMA_TO_DEVICE) {
> memcpy(dma_addr, buffer + offset, sz);
> - else
> + swiotlb_dma_sync(dma_addr, sz, dir);
> + } else {
> + swiotlb_dma_sync(dma_addr, sz, dir);
> memcpy(buffer + offset, dma_addr, sz);
> + }
> kunmap_atomic(buffer, KM_BOUNCE_READ);
> local_irq_restore(flags);
>
> @@ -359,10 +362,14 @@ static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
> offset = 0;
> }
> } else {
> - if (dir == DMA_TO_DEVICE)
> + if (dir == DMA_TO_DEVICE) {
> memcpy(dma_addr, phys_to_virt(phys), size);
> - else
> + swiotlb_dma_sync(dma_addr, size, dir);
> +
> + } else {
> + swiotlb_dma_sync(dma_addr, size, dir);
> memcpy(phys_to_virt(phys), dma_addr, size);
> + }
> }
> }
>
> @@ -542,6 +549,8 @@ sync_single(struct device *hwdev, char *dma_addr, size_t size,
> }
> }
>
> +#ifndef CONFIG_NOT_COHERENT_CACHE
> +
> void *
> swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> dma_addr_t *dma_handle, gfp_t flags)
> @@ -606,6 +615,8 @@ swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
> }
> EXPORT_SYMBOL(swiotlb_free_coherent);
>
> +#endif /* !CONFIG_NOT_COHERENT_CACHE */
> +
> static void
> swiotlb_full(struct device *dev, size_t size, int dir, int do_panic)
> {
> @@ -652,8 +663,10 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> * we can safely return the device addr and not worry about bounce
> * buffering it.
> */
> - if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
> + if (dma_capable(dev, dev_addr, size) && !swiotlb_force) {
> + swiotlb_dma_sync_page(page, offset, size, dir);
> return dev_addr;
> + }
>
> /*
> * Oh well, have to allocate and map a bounce buffer.
> @@ -739,6 +752,8 @@ swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
> return;
> }
>
> + swiotlb_dma_sync(phys_to_virt(paddr), size, dir);
> +
> if (dir != DMA_FROM_DEVICE)
> return;
>
> @@ -835,8 +850,11 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
> return 0;
> }
> sg->dma_address = swiotlb_virt_to_bus(hwdev, map);
> - } else
> + } else {
> + swiotlb_dma_sync_page(sg_page(sg), sg->offset,
> + sg->length, dir);
> sg->dma_address = dev_addr;
> + }
> sg->dma_length = sg->length;
> }
> return nelems;
> --
> 1.6.3.3
>
> --
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