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Re: [PATCHv7 9/9] ARM: dma-mapping: add support for IOMMU mapper

Hi KyongHo,

On 03/22/2012 07:29 PM, Subash Patel wrote:
Hi KyongHo,

On 03/21/2012 05:26 AM, KyongHo Cho wrote:
On Tue, Mar 20, 2012 at 10:50 PM, Subash Patel<subashrp@xxxxxxxxx> wrote:
Sorry for digging this very late. But as part of integrating dma_map v7&
sysmmu v12 on 3.3-rc5, I am facing below issue:

a) By un-selecting IOMMU in menu config, I am able to allocate memory in

b) When I enable SYSMMU support for the IP's, I am receiving below

Unhandled fault: external abort on non-linefetch (0x818) at 0xb6f55000

I think this has something to do with the access to the SYSMMU
registers for
writing the page table. Has anyone of you faced this issue while testing
these(dma_map+iommu) patches on kernel mentioned above? This must be
something related to recent changes, as I didn't have issues with these
patches on 3.2 kernel.

0xb6f55000 is not an address of SYSMMU register if your kernel starts
at 0xc0000000.

Can you tell me any detailed information or situation?
I hate to say this, but I am not able to catch the fault location even
with JTAG. Once the fault comes, the debugger looses all control over. I
think now possible method is reproduction at your end :)

Thanks to you, Issue is now figured out. This was due to generic Power Domain code added recently. SYSMMU registers were not getting enabled due to this. I reverted the PD changes from the machine to architecture specific, and voila, SYSMMU is back into action using the dma-mapping-v7. I will have to see how the same would behave when the complete PD changes comes to mainline from maintainers for-next in future.


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