From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 12/16] iommu/amd: Add initialization routines for AMD interrupt remapping Date: Mon, 1 Oct 2012 10:05:41 +0200 Message-ID: <20121001080541.GM4009@amd.com> References: <1348835046-3262-1-git-send-email-joerg.roedel@amd.com> <1348835046-3262-13-git-send-email-joerg.roedel@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Shuah Khan Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org 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 -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632