Re: [PATCH 1/1] unify DMA_..BIT_MASK definitions: v3.1

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 05 Oct 2007 13:43:54 -0700
Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Andrew Morton wrote:
> > From: Andrew Morton <akpm@linux-foundation.org>
> >
> > Now that we have DMA_BIT_MASK(), these macros are pointless.
> >   
> 
> Except, unfortunately, DMA_64BIT_MASK.  I guess we could special case
> it, assuming this works in all the contexts the macro is used in (ie,
> compile-time constant?):
> 
> #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
> 

doh.  Thanks.

--- a/include/linux/dma-mapping.h~stop-using-dma_xxbit_mask-fix
+++ a/include/linux/dma-mapping.h
@@ -13,7 +13,7 @@ enum dma_data_direction {
 	DMA_NONE = 3,
 };
 
-#define DMA_BIT_MASK(n)	((1ULL<<(n))-1)
+#define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 
 /*
  * NOTE: do not use the below macros in new code and do not add new definitions
@@ -21,7 +21,7 @@ enum dma_data_direction {
  *
  * Instead, just open-code DMA_BIT_MASK(n) within your driver
  */
-#define DMA_64BIT_MASK	(~0ULL)
+#define DMA_64BIT_MASK	DMA_BIT_MASK(64)
 #define DMA_48BIT_MASK	DMA_BIT_MASK(48)
 #define DMA_47BIT_MASK	DMA_BIT_MASK(47)
 #define DMA_40BIT_MASK	DMA_BIT_MASK(40)
_


it's irksome that there doesn't seem to be a neater way of doing
this, until they give us unsigned long long longs.