From: Jake Moilanen Date: Fri, 2 Mar 2007 21:49:43 +0000 (-0600) Subject: [POWERPC] DMA 4GB boundary protection X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=618d3adc351a24c4c48437c767befb88ca2d199d;p=linux-beck.git [POWERPC] DMA 4GB boundary protection There are many adapters which can not handle DMAing acrosss any 4 GB boundary. For instance the latest Emulex adapters. This normally is not an issue as firmware gives us dma-windows under 4gigs. However, some of the new System-P boxes have dma-windows above 4gigs, and this present a problem. I propose fixing it in the IOMMU allocation instead of making each driver protect against it as it is more efficient, and won't require changing every driver which has not considered this issue. This patch checks to see if the mapping spans a 4 gig boundary, and if it does, retries the allocation. It tries the next allocation at the start of the crossed 4 gig boundary. Signed-off-by: Jake Moilanen Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 95edad4faf26..c50d7072f305 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -76,6 +76,7 @@ static unsigned long iommu_range_alloc(struct iommu_table *tbl, unsigned int align_order) { unsigned long n, end, i, start; + unsigned long start_addr, end_addr; unsigned long limit; int largealloc = npages > 15; int pass = 0; @@ -146,6 +147,15 @@ static unsigned long iommu_range_alloc(struct iommu_table *tbl, } } + /* DMA cannot cross 4 GB boundary */ + start_addr = (n + tbl->it_offset) << PAGE_SHIFT; + end_addr = (end + tbl->it_offset) << PAGE_SHIFT; + if ((start_addr >> 32) != (end_addr >> 32)) { + end_addr &= 0xffffffff00000000l; + start = (end_addr >> PAGE_SHIFT) - tbl->it_offset; + goto again; + } + for (i = n; i < end; i++) if (test_bit(i, tbl->it_map)) { start = i+1;