dma_alloc_coherent

[Kartik Babu <kbabu@automatika.com>]

  I'm trying to replace consistent_alloc in a driver that was written 
for the 2.4 kernel with dma_alloc_coherent. My question is that I do not 
use a struct device * pointer at all. Browsing through the source for 
the 2.6.12
on ARM XScale PXA255, I see that this argument may be NULL.

 Still, I'd like to know if passing NULL has any side effects. If so, 
what are they?

 I do however have a cdev structure taht I use for device registration, 
but I do not see how that would help.

Thanks
Kartik