Re: [PATCH] iommu/ipmmu-vmsa: Drop LPAE Kconfig dependency

From: Magnus Damm
Date: Tue Oct 20 2015 - 04:55:25 EST


Hi Laurent,

On Mon, Oct 19, 2015 at 3:42 PM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> Hi Magnus,
>
> Thank you for the patch.
>
> On Monday 19 October 2015 12:02:53 Magnus Damm wrote:
>> From: Magnus Damm <damm+renesas@xxxxxxxxxxxxx>
>>
>> Neither the ARM page table code enabled by IOMMU_IO_PGTABLE_LPAE
>> nor the IPMMU_VMSA driver actually depends on ARM_LPAE, so get
>> rid of the dependency.
>>
>> Tested with ipmmu-vmsa on r8a7794 ALT and a kernel config using:
>> # CONFIG_ARM_LPAE is not set
>
> The driver only supports the 40-bits page table format for now, hence the
> dependency on LPAE, but it indeed seems that the dependency is bogus. As long
> as the 8 MSBs of the translated address are all 0 I assume the output 40-bit
> address is usable on a 32-bit physical address system.
>
> How have you tested the patch ?

Modetest with local IPMMUMX enablement on r8a7794 ALT.

Cheers,

/ magnus
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