On Friday 09 May 2008 12:06:55 am Takashi Iwai wrote:
Thanks for catching it. Yeah, the patch looks buggy. We had an implicit assumption that dev = NULL for ISA devices that require 24bit DMA.
Naive question #1: Why don't we have a struct device for these ISA devices? PNP builds a struct device with DMA_24BIT_MASK for ISAPNP devices.
Naive question #2: Do other architectures need similar fixes in dma_alloc_coherent()?
[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