From: Russell King Date: Tue, 6 Feb 2007 17:29:53 +0000 (+0000) Subject: [ARM] Don't call consistent_sync() for DMA coherent memory X-Git-Tag: v2.6.21-rc1~75^2~6^6~8 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f8e33546d17c7d8849be3a6623c3b6b3c9b588b;p=linux-2.6 [ARM] Don't call consistent_sync() for DMA coherent memory Memory allocated by the coherent memory allocators will be marked uncacheable, which means it's pointless calling consistent_sync() to perform cache maintainence on this memory; it's just a waste of CPU cycles. Moreover, with the (subsequent) merge of outer cache support, it actually breaks things to call consistent_sync() on anything but direct-mapped memory. Signed-off-by: Russell King --- diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c index 2e635b814c..272702accd 100644 --- a/arch/arm/common/dmabounce.c +++ b/arch/arm/common/dmabounce.c @@ -281,10 +281,14 @@ map_single(struct device *dev, void *ptr, size_t size, ptr = buf->safe; dma_addr = buf->safe_dma_addr; + } else { + /* + * We don't need to sync the DMA buffer since + * it was allocated via the coherent allocators. + */ + consistent_sync(ptr, size, dir); } - consistent_sync(ptr, size, dir); - return dma_addr; } @@ -397,7 +401,10 @@ sync_single(struct device *dev, dma_addr_t dma_addr, size_t size, default: BUG(); } - consistent_sync(buf->safe, size, dir); + /* + * No need to sync the safe buffer - it was allocated + * via the coherent allocators. + */ } else { consistent_sync(dma_to_virt(dev, dma_addr), size, dir); }