lkml.org 
[lkml]   [2004]   [Jun]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH] dma_get_required_mask()
    From
    Date
    Following the discussion, this is a patch implementing
    dma_get_required_mask(). The default implementation simply works out
    the largest mask covering all of memory and returns the and of that with
    the current dma_mask. If this looks OK, I'll send out another patch
    including the documentation updates as well.

    I've put the implementation in linux/dma-mapping.h with a
    ARCH_HAS_DMA_GET_REQUIRED_MASK override for those architectures that
    would like to do something different.

    Any opinions on whether I should also make linux/dma-mapping.h include
    linux/bitops.h now since it requires fls() from there?

    James

    ===== include/linux/dma-mapping.h 1.3 vs edited =====
    --- 1.3/include/linux/dma-mapping.h 2004-03-30 20:53:54 -05:00
    +++ edited/include/linux/dma-mapping.h 2004-06-25 11:12:30 -04:00
    @@ -19,6 +19,29 @@
    #define dma_sync_single dma_sync_single_for_cpu
    #define dma_sync_sg dma_sync_sg_for_cpu

    +#ifndef ARCH_HAS_DMA_GET_REQUIRED_MASK
    +static inline u64 dma_get_required_mask(struct device *dev)
    +{
    + extern unsigned long max_pfn; /* defined in bootmem.h but may
    + not be included */
    + u32 low_totalram = ((max_pfn - 1) << PAGE_SHIFT);
    + u32 high_totalram = ((max_pfn - 1) >> (32 - PAGE_SHIFT));
    + u64 mask;
    +
    + if (!high_totalram) {
    + /* convert to mask just covering totalram */
    + low_totalram = (1 << (fls(low_totalram) - 1));
    + low_totalram += low_totalram - 1;
    + mask = low_totalram;
    + } else {
    + high_totalram = (1 << (fls(high_totalram) - 1));
    + high_totalram += high_totalram - 1;
    + mask = (((u64)high_totalram) << 32) + 0xffffffff;
    + }
    + return mask & *dev->dma_mask;
    +}
    +#endif
    +
    #endif


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:04    [W:0.036 / U:6.956 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site