linux-kernel - Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm

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Message-ID: <20181123183555.GE21183@arm.com>
Date:   Fri, 23 Nov 2018 18:36:01 +0000
From:   Will Deacon <will.deacon@....com>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, alex.williamson@...hat.com,
        Linux PM <linux-pm@...r.kernel.org>, sboyd@...nel.org,
        freedreno <freedreno@...ts.freedesktop.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        open list <linux-kernel@...r.kernel.org>,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>," <iommu@...ts.linux-foundation.org>,
        robh+dt <robh+dt@...nel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm_runtime during
 probe, add/remove device

On Thu, Nov 22, 2018 at 05:32:24PM +0530, Vivek Gautam wrote:
> Hi Will,
> 
> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@....com> wrote:
> >
> > On Fri, Nov 16, 2018 at 04:54:27PM +0530, Vivek Gautam wrote:
> > > From: Sricharan R <sricharan@...eaurora.org>
> > >
> > > The smmu device probe/remove and add/remove master device callbacks
> > > gets called when the smmu is not linked to its master, that is without
> > > the context of the master device. So calling runtime apis in those places
> > > separately.
> > > Global locks are also initialized before enabling runtime pm as the
> > > runtime_resume() calls device_reset() which does tlb_sync_global()
> > > that ultimately requires locks to be initialized.
> > >
> > > Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> > > [vivek: Cleanup pm runtime calls]
> > > Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
> > > Reviewed-by: Tomasz Figa <tfiga@...omium.org>
> > > Tested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> > > Reviewed-by: Robin Murphy <robin.murphy@....com>
> > > ---
> > >  drivers/iommu/arm-smmu.c | 101 ++++++++++++++++++++++++++++++++++++++++++-----
> > >  1 file changed, 91 insertions(+), 10 deletions(-)
> >
> > Given that you're doing the get/put in the TLBI ops unconditionally:
> >
> > >  static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain)
> > >  {
> > >       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> > > +     struct arm_smmu_device *smmu = smmu_domain->smmu;
> > >
> > > -     if (smmu_domain->tlb_ops)
> > > +     if (smmu_domain->tlb_ops) {
> > > +             arm_smmu_rpm_get(smmu);
> > >               smmu_domain->tlb_ops->tlb_flush_all(smmu_domain);
> > > +             arm_smmu_rpm_put(smmu);
> > > +     }
> > >  }
> > >
> > >  static void arm_smmu_iotlb_sync(struct iommu_domain *domain)
> > >  {
> > >       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> > > +     struct arm_smmu_device *smmu = smmu_domain->smmu;
> > >
> > > -     if (smmu_domain->tlb_ops)
> > > +     if (smmu_domain->tlb_ops) {
> > > +             arm_smmu_rpm_get(smmu);
> > >               smmu_domain->tlb_ops->tlb_sync(smmu_domain);
> > > +             arm_smmu_rpm_put(smmu);
> > > +     }
> >
> > Why do you need them around the map/unmap calls as well?
> 
> We still have .tlb_add_flush path?

Ok, so we could add the ops around that as well. Right now, we've got
the runtime pm hooks crossing two parts of the API.

Will