At Fri, 09 May 2008 03:37:54 +0200, Rene Herman wrote:
Good day.
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.
It won't just revert due to 32/64 merge.
Rene.
Thanks for catching it. Yeah, the patch looks buggy. We had an implicit assumption that dev = NULL for ISA devices that require 24bit DMA.
How about the patch below? It's against the latest Linus git tree.
thanks,
Takashi
[PATCH] x86: Fix dma_alloc_coherent() for ISA devices
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.
Signed-off-by: Takashi Iwai tiwai@suse.de
---
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 0c37f16..c5ef1af 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