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Date: Mon, 13 Aug 2012 13:54:47 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Huacai Chen <chenhuacai@...il.com>
Cc: Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
linux-kernel@...r.kernel.org, Fuxin Zhang <zhangfx@...ote.com>,
Zhangjin Wu <wuzhangjin@...il.com>,
Huacai Chen <chenhc@...ote.com>,
Hongliang Tao <taohl@...ote.com>, Hua Yan <yanh@...ote.com>
Subject: Re: [PATCH V5 09/18] MIPS: Loongson: Add swiotlb to support big
memory (>4GB).
> +static void *loongson_dma_alloc_coherent(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t gfp, struct dma_attrs *attrs)
> +{
> + void *ret;
> +
> + if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
> + return ret;
> +
> + /* ignore region specifiers */
> + gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
> +
> +#ifdef CONFIG_ZONE_DMA
> + if (dev == NULL)
> + gfp |= __GFP_DMA;
When would this happen? dev == NULL?
> + else if (dev->coherent_dma_mask <= DMA_BIT_MASK(24))
> + gfp |= __GFP_DMA;
> + else
> +#endif
> +#ifdef CONFIG_ZONE_DMA32
> + if (dev->coherent_dma_mask <= DMA_BIT_MASK(32))
> + gfp |= __GFP_DMA32;
> + else
Why the 'else'
> +#endif
> + ;
why?
> + gfp |= __GFP_NORETRY;
> +
> + ret = swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
> + mb();
Why the 'mb()' ? Can you just do
return swiotlb_alloc_coherent(...)
> + return ret;
> +}
> +
> +static void loongson_dma_free_coherent(struct device *dev, size_t size,
> + void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs)
> +{
> + int order = get_order(size);
> +
> + if (dma_release_from_coherent(dev, order, vaddr))
> + return;
> +
> + swiotlb_free_coherent(dev, size, vaddr, dma_handle);
> +}
> +
> +static dma_addr_t loongson_dma_map_page(struct device *dev, struct page *page,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir,
> + struct dma_attrs *attrs)
> +{
> + dma_addr_t daddr = swiotlb_map_page(dev, page, offset, size,
> + dir, attrs);
> + mb();
Please do 'return swiotlb_map_page(..)'..
But if you are doing that why don't you just set the dma_ops.map_page = swiotlb_map_page
?
> + return daddr;
> +}
> +
> +static int loongson_dma_map_sg(struct device *dev, struct scatterlist *sg,
> + int nents, enum dma_data_direction dir,
> + struct dma_attrs *attrs)
> +{
> + int r = swiotlb_map_sg_attrs(dev, sg, nents, dir, NULL);
> + mb();
> +
> + return r;
> +}
> +
> +static void loongson_dma_sync_single_for_device(struct device *dev,
> + dma_addr_t dma_handle, size_t size,
> + enum dma_data_direction dir)
> +{
> + swiotlb_sync_single_for_device(dev, dma_handle, size, dir);
> + mb();
> +}
> +
> +static void loongson_dma_sync_sg_for_device(struct device *dev,
> + struct scatterlist *sg, int nents,
> + enum dma_data_direction dir)
> +{
> + swiotlb_sync_sg_for_device(dev, sg, nents, dir);
> + mb();
> +}
> +
I am not really sure why you have these extra functions, when you could
just modify the dma_ops to point to the swiotlb ones
> +static dma_addr_t loongson_unity_phys_to_dma(struct device *dev, phys_addr_t paddr)
> +{
> + return (paddr < 0x10000000) ?
> + (paddr | 0x0000000080000000) : paddr;
> +}
> +
> +static phys_addr_t loongson_unity_dma_to_phys(struct device *dev, dma_addr_t daddr)
> +{
> + return (daddr < 0x90000000 && daddr >= 0x80000000) ?
> + (daddr & 0x0fffffff) : daddr;
> +}
> +
> +struct loongson_dma_map_ops {
> + struct dma_map_ops dma_map_ops;
> + 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);
> +};
> +
> +dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +{
> + struct loongson_dma_map_ops *ops = container_of(get_dma_ops(dev),
> + struct loongson_dma_map_ops, dma_map_ops);
> +
> + return ops->phys_to_dma(dev, paddr);
> +}
> +
> +phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +{
> + struct loongson_dma_map_ops *ops = container_of(get_dma_ops(dev),
> + struct loongson_dma_map_ops, dma_map_ops);
> +
> + return ops->dma_to_phys(dev, daddr);
> +}
> +
> +static int loongson_dma_set_mask(struct device *dev, u64 mask)
> +{
> + /* Loongson doesn't support DMA above 32-bit */
> + if (mask > DMA_BIT_MASK(32))
> + return -EIO;
> +
> + *dev->dma_mask = mask;
> +
> + return 0;
> +}
> +
> +static struct loongson_dma_map_ops loongson_linear_dma_map_ops = {
> + .dma_map_ops = {
> + .alloc = loongson_dma_alloc_coherent,
> + .free = loongson_dma_free_coherent,
> + .map_page = loongson_dma_map_page,
But why not 'swiotlb_map_page'?
> + .unmap_page = swiotlb_unmap_page,
> + .map_sg = loongson_dma_map_sg,
> + .unmap_sg = swiotlb_unmap_sg_attrs,
> + .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
> + .sync_single_for_device = loongson_dma_sync_single_for_device,
> + .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
> + .sync_sg_for_device = loongson_dma_sync_sg_for_device,
> + .mapping_error = swiotlb_dma_mapping_error,
> + .dma_supported = swiotlb_dma_supported,
> + .set_dma_mask = loongson_dma_set_mask
> + },
> + .phys_to_dma = loongson_unity_phys_to_dma,
> + .dma_to_phys = loongson_unity_dma_to_phys
Why do you need these? I am not seeing it being used here by any external code?
> +};
> +
> +void __init plat_swiotlb_setup(void)
> +{
> + swiotlb_init(1);
> + mips_dma_map_ops = &loongson_linear_dma_map_ops.dma_map_ops;
> +}
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index 3fab204..122f4f8 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -42,6 +42,13 @@ static inline int cpu_is_noncoherent_r10000(struct device *dev)
> current_cpu_type() == CPU_R12000);
> }
>
> +static inline int cpu_is_noncoherent_loongson(struct device *dev)
> +{
> + return !plat_device_is_coherent(dev) &&
> + (current_cpu_type() == CPU_LOONGSON2 ||
> + current_cpu_type() == CPU_LOONGSON3);
> +}
> +
> static gfp_t massage_gfp_flags(const struct device *dev, gfp_t gfp)
> {
> gfp_t dma_flag;
> @@ -209,7 +216,7 @@ static inline void __dma_sync(struct page *page,
> static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,
> size_t size, enum dma_data_direction direction, struct dma_attrs *attrs)
> {
> - if (cpu_is_noncoherent_r10000(dev))
> + if (cpu_is_noncoherent_r10000(dev) || cpu_is_noncoherent_loongson(dev))
> __dma_sync(dma_addr_to_page(dev, dma_addr),
> dma_addr & ~PAGE_MASK, size, direction);
>
> @@ -260,7 +267,7 @@ static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
> static void mips_dma_sync_single_for_cpu(struct device *dev,
> dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
> {
> - if (cpu_is_noncoherent_r10000(dev))
> + if (cpu_is_noncoherent_r10000(dev) || cpu_is_noncoherent_loongson(dev))
> __dma_sync(dma_addr_to_page(dev, dma_handle),
> dma_handle & ~PAGE_MASK, size, direction);
> }
> @@ -281,7 +288,7 @@ static void mips_dma_sync_sg_for_cpu(struct device *dev,
>
> /* Make sure that gcc doesn't leave the empty loop body. */
> for (i = 0; i < nelems; i++, sg++) {
> - if (cpu_is_noncoherent_r10000(dev))
> + if (cpu_is_noncoherent_r10000(dev) || cpu_is_noncoherent_loongson(dev))
> __dma_sync(sg_page(sg), sg->offset, sg->length,
> direction);
> }
> --
> 1.7.7.3
>
> --
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