Re: consistent_alloc() on PPC

On Thu, Jan 20, 2005 at 10:00:47PM +0530, Sachin P wrote:

Hi,
Thanks a lot to all of you for the help . 
The following is a more clearer version of the problem I am facing :

1.I am porting drivers from X86 (running Linux 2.4-20) to 
  PPC platform running (Montevista Linux-2.4.20).
2.In  wrapper function for DMA allocation, I am using 
  consistent_alloc() to allocate the memory. This function gives me
  both the virtual-address as well as the dma-address.
  I pass both these values to the upper-level drivers.
3. However , once the upper-level drivers are done with the memory
   they call the wrapper function for free dma and pass only the dma
   address and not the virtual-address. However consistent_free() 
   accepts only virtual-address. 
   Hence I need a way to convert the dma address to the
   virtual-address.  

All you need to do is cache the virtual address and the dma/phys
address for later use when calling consistent_free(). converting
random DMA/phys to virtual is a bad idea since you are going to
find multiple mappings. Cache the results in your driver...it's
trivial.

-Matt