linux-kernel - Re: [PATCH 12/16] iommu/amd: Add initialization routines for AMD interrupt remapping

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Date:	Mon, 1 Oct 2012 10:05:41 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Shuah Khan <shuahkhan@...il.com>
CC:	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 12/16] iommu/amd: Add initialization routines for AMD
 interrupt remapping

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.

>> > +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.


	Joerg

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