Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=32e8f70230c0c417490787b3f48b6ed6c48e7ec9
Commit:     32e8f70230c0c417490787b3f48b6ed6c48e7ec9
Parent:     64da82efae0d7b5f7c478021840fd329f76d965d
Author:     James Bottomley <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 01:23:55 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Oct 16 09:42:50 2007 -0700

    introduce DMA_MASK_NONE as a signal for unable to do DMA
    
    Some devices are incapable of DMA and need to be recognised as such.
    Introduce a NONE dma mask to facilitate this plus an inline function:
    is_device_dma_capable() to check this.
    
    Signed-off-by: James Bottomley <[EMAIL PROTECTED]>
    Cc: Andi Kleen <[EMAIL PROTECTED]>
    Cc: Alan Cox <[EMAIL PROTECTED]>
    Cc: Tejun Heo <[EMAIL PROTECTED]>
    Cc: Natalie Protasevich <[EMAIL PROTECTED]>
    Cc: Jeff Garzik <[EMAIL PROTECTED]>
    Cc: Dominik Brodowski <[EMAIL PROTECTED]>
    Cc: Russell King <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 include/linux/dma-mapping.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2dc21cb..0ebfafb 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -24,6 +24,8 @@ enum dma_data_direction {
 #define DMA_28BIT_MASK 0x000000000fffffffULL
 #define DMA_24BIT_MASK 0x0000000000ffffffULL
 
+#define DMA_MASK_NONE  0x0ULL
+
 static inline int valid_dma_direction(int dma_direction)
 {
        return ((dma_direction == DMA_BIDIRECTIONAL) ||
@@ -31,6 +33,11 @@ static inline int valid_dma_direction(int dma_direction)
                (dma_direction == DMA_FROM_DEVICE));
 }
 
+static inline int is_device_dma_capable(struct device *dev)
+{
+       return dev->dma_mask != NULL && *dev->dma_mask != DMA_MASK_NONE;
+}
+
 #ifdef CONFIG_HAS_DMA
 #include <asm/dma-mapping.h>
 #else
-
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