Re: [PATCH 12/16] iommu/amd: Add initialization routines for AMDinterrupt remapping

From: Shuah Khan
Date: Mon Oct 01 2012 - 12:02:27 EST


On Mon, Oct 1, 2012 at 2:05 AM, Joerg Roedel <joerg.roedel@xxxxxxx> wrote:
> On Fri, Sep 28, 2012 at 05:18:18PM -0600, Shuah Khan wrote:
>> > +void amd_iommu_disable(void)
>> > +{
>> > + amd_iommu_suspend();
>>
>> Is it safe to attempt to suspend when iommu is in suspend state? In
>> other words what happens if amd_iommu_disable() gets called when iommu
>> is already in suspend state?
>
> Yes, this is safe. It just trns a bit to 0 which is already 0.
>
Good.
>>> > +int amd_iommu_reenable(int mode)
>> > +{
>> > + amd_iommu_resume();
>>
>> Same question as above. Safe to do a resume, when in resumed state?
>
> Safe too, it just writes values to the hardware which are already there.
> This was also proven by testing.
>

Thanks. Sounds good.

-- Shuah
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