Re: RDMA/cxgb4: Support on-chip SQs

[Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

On 1/30/2013 3:45 PM, Dan Carpenter wrote:
> On Wed, Jan 30, 2013 at 03:36:48PM -0600, Steve Wise wrote:
>> I wonder, then, what the correct service is to get the cpu physical
>> address from a kernel virtual address returned from
>> dma_alloc_coherent()?  I think this is correct as-is, since I think
>> dma_alloc_coherent() falls under the "directly mapped" addresses in
>> the virt_to_phys() prototype comment.
>>
> Here is another relevant comment I should have included.
>
> commit ae6a5d37725853325a2b3460165fbc5613ce2916
> Author: Russell King <rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
> Date:   Tue Nov 20 12:17:51 2012 +0000
>
>      ASoC: kirkwood-dma: fix use of virt_to_phys()
>
>      This is part of a patch found in Rabeeh Khoury's git tree for the
>      cubox.
>
>      You can not use virt_to_phys() on the address returned from
>      dma_alloc_coherent(); it may not be part of the kernel direct-mapped
>      memory.  Fix this to use the DMA address instead.
>
>      Signed-off-by: Russell King <rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
>      Signed-off-by: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
>
> I don't know the details though, and I certainly don't know how
> someone would fix this.  ;)
>

How do I map the dma address into a physical address suitable for 
passing to remap_pfn_range()?

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