* Ingo Molnar mingo@elte.hu wrote:
good catch! Queued it up for testing. Jesse, do you concur?
here's the patch below, tidied up.
Ingo
-------------------------------> Subject: x86/pci: fix broken ISA DMA From: Takashi Iwai tiwai@suse.de Date: Fri, 09 May 2008 08:06:55 +0200
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 rene.herman@keyaccess.nl Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Ingo Molnar mingo@elte.hu --- arch/x86/kernel/pci-dma.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
Index: linux-x86.q/arch/x86/kernel/pci-dma.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/pci-dma.c +++ linux-x86.q/arch/x86/kernel/pci-dma.c @@ -386,11 +386,13 @@ dma_alloc_coherent(struct device *dev, s 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) @@ -404,7 +406,7 @@ dma_alloc_coherent(struct device *dev, s 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