linux-kernel - [PATCH 2/2] x86: gart alloc_coherent does virtual mapppings only when necessary

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Message-Id: <1221142128-28350-3-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Date:	Thu, 11 Sep 2008 23:08:48 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	mingo@...hat.com
Cc:	linux-kernel@...r.kernel.org, fujita.tomonori@....ntt.co.jp,
	Joerg Roedel <joerg.roedel@....com>
Subject: [PATCH 2/2] x86: gart alloc_coherent does virtual mapppings only when necessary

gart alloc_coherent need to do virtual mapppings only when an
allocated buffer is not DMA-capable for a device.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Cc: Joerg Roedel <joerg.roedel@....com>
---
 arch/x86/kernel/pci-gart_64.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index 1b0c412..47abe43 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -488,15 +488,23 @@ gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
 		    gfp_t flag)
 {
 	void *vaddr;
+	dma_addr_t paddr;
 	unsigned long align_mask;
+	u64 dma_mask = dma_alloc_coherent_mask(dev, flag);
 
 	vaddr = (void *)__get_free_pages(flag | __GFP_ZERO, get_order(size));
 	if (!vaddr)
 		return NULL;
 
+	paddr = virt_to_phys(vaddr);
+	if (is_buffer_dma_capable(dma_mask, paddr, size)) {
+		*dma_addr = paddr;
+		return vaddr;
+	}
+
 	align_mask = (1UL << get_order(size)) - 1;
 
-	*dma_addr = dma_map_area(dev, __pa(vaddr), size, DMA_BIDIRECTIONAL,
+	*dma_addr = dma_map_area(dev, paddr, size, DMA_BIDIRECTIONAL,
 				 align_mask);
 	flush_gart();
 
-- 
1.5.4.2

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