From 5abc100e882a979f8f5be8184938305b3fb2df2b Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 20 Jun 2005 12:31:14 +0100 Subject: [PATCH] [PATCH] ARM: Ensure DMA-bounced buffers are properly written to RAM When DMA bounce buffers were unmapped and the data was memcpy'd to the original buffer, we were not ensuring that the data was written to RAM. This means that there was the potential for page cache pages to have different cache states depending whether they've been bounced or not. Signed-off-by: Russell King --- arch/arm/common/dmabounce.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c index 5797b1b100a1..39dd33ff6f37 100644 --- a/arch/arm/common/dmabounce.c +++ b/arch/arm/common/dmabounce.c @@ -302,12 +302,24 @@ unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, DO_STATS ( device_info->bounce_count++ ); - if ((dir == DMA_FROM_DEVICE) || - (dir == DMA_BIDIRECTIONAL)) { + if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { + unsigned long ptr; + dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", __func__, buf->safe, buf->ptr, size); memcpy(buf->ptr, buf->safe, size); + + /* + * DMA buffers must have the same cache properties + * as if they were really used for DMA - which means + * data must be written back to RAM. Note that + * we don't use dmac_flush_range() here for the + * bidirectional case because we know the cache + * lines will be coherent with the data written. + */ + ptr = (unsigned long)buf->ptr; + dmac_clean_range(ptr, ptr + size); } free_safe_buffer(device_info, buf); }