lkml.org 
[lkml]   [2008]   [May]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: 2.6.26-rc1 regression: ISA DMA broken (bisected)
    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


    \
     
     \ /
      Last update: 2008-05-09 08:09    [W:0.022 / U:60.808 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site