powerpc/64: Honor swiotlb limit in coherent allocations (6397fc3f) · Commits · 戴 / test

FSL PCI cannot directly address the whole lower 4 GiB due to conflicts with PCICSRBAR and outbound windows, and thus max_direct_dma_addr is less than 4GiB. Honor that limit in dma_direct_alloc_coherent(). Note that setting the DMA mask to 31 bits is not an option, since many PCI drivers would fail if we reject 32-bit DMA in dma_supported(), and we have no control over the setting of coherent_dma_mask if dma_supported() returns true. Signed-off-by:

Scott Wood <scottwood@freescale.com> Cc: Shaohui Xie <Shaohui.Xie@freescale.com>

arch/powerpc/kernel/dma.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <asm/vio.h>
		#include <asm/bug.h>
		#include <asm/machdep.h>
		#include <asm/swiotlb.h>

		/*
		* Generic direct DMA implementation
		@@ -25,6 +26,18 @@
		* default the offset is PCI_DRAM_OFFSET.
		*/

		static u64 __maybe_unused get_pfn_limit(struct device *dev)
		{
		u64 pfn = (dev->coherent_dma_mask >> PAGE_SHIFT) + 1;
		struct dev_archdata __maybe_unused *sd = &dev->archdata;

		#ifdef CONFIG_SWIOTLB
		if (sd->max_direct_dma_addr && sd->dma_ops == &swiotlb_dma_ops)
		pfn = min_t(u64, pfn, sd->max_direct_dma_addr >> PAGE_SHIFT);
		#endif

		return pfn;
		}

		void dma_direct_alloc_coherent(struct device dev, size_t size,
		dma_addr_t *dma_handle, gfp_t flag,
		@@ -40,7 +53,7 @@ void dma_direct_alloc_coherent(struct device dev, size_t size,
		#else
		struct page *page;
		int node = dev_to_node(dev);
		u64 pfn = (dev->coherent_dma_mask >> PAGE_SHIFT) + 1;
		u64 pfn = get_pfn_limit(dev);
		int zone;

		zone = dma_pfn_limit_to_zone(pfn);

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