From: Takashi Iwai Date: Fri, 9 May 2008 06:06:55 +0000 (+0200) Subject: x86/PCI: fix broken ISA DMA X-Git-Tag: v2.6.26-rc3~70^2~6 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4a367f3a9dbf2e7ffcee4702203479809236ee6e;p=linux-2.6 x86/PCI: fix broken ISA DMA Rene Herman reported: > commit 8779f2fc3b84ebb6c5181fb13d702e9944c16069 > > "x86: don't try to allocate from DMA zone at first" > > breaks all of ISA DMA. Or all of ALSA ISA DMA at least. All > ISA soundcards are silent following that commit -- no error > messages, everything appears fine, just silence. That patch is buggy. We had an implicit assumption that dev = NULL for ISA devices that require 24bit DMA. The recent work on x86 dma_alloc_coherent() breaks the ISA DMA buffer allocation, which is represented by "dev = NULL" and requires 24bit DMA implicitly. Bisected-by: Rene Herman Signed-off-by: Takashi Iwai Signed-off-by: Ingo Molnar Signed-off-by: Jesse Barnes --- diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 0c37f16b69..c5ef1af8e7 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -385,11 +385,13 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, if (dma_alloc_from_coherent_mem(dev, size, dma_handle, &memory)) return memory; - if (!dev) + if (!dev) { dev = &fallback_dev; + gfp |= GFP_DMA; + } dma_mask = dev->coherent_dma_mask; if (dma_mask == 0) - dma_mask = DMA_32BIT_MASK; + dma_mask = (gfp & GFP_DMA) ? DMA_24BIT_MASK : DMA_32BIT_MASK; /* Device not DMA able */ if (dev->dma_mask == NULL) @@ -403,7 +405,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, larger than 16MB and in this case we have a chance of finding fitting memory in the next higher zone first. If not retry with true GFP_DMA. -AK */ - if (dma_mask <= DMA_32BIT_MASK) + if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA)) gfp |= GFP_DMA32; #endif