Messages in this thread | | | Date | Fri, 09 May 2008 09:48:59 -0300 | From | Glauber Costa <> | Subject | Re: 2.6.26-rc1 regression: ISA DMA broken (bisected) |
| |
Takashi Iwai wrote: > 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>
Woke up and saw it, got worried, but there is already a fix. ;-)
Nice work! And thank you
> --- > > 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 >
| |