linux-kernel - Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm

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Date:   Fri, 7 Sep 2018 15:52:06 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     Tomasz Figa <tfiga@...omium.org>,
        Robin Murphy <robin.murphy@....com>
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,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Will Deacon <will.deacon@....com>,
        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>,
        freedreno <freedreno@...ts.freedesktop.org>
Subject: Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm_runtime during probe,
 add/remove device

On Fri, Sep 7, 2018 at 3:22 PM Tomasz Figa <tfiga@...omium.org> wrote:
>
> On Fri, Sep 7, 2018 at 6:38 PM Vivek Gautam <vivek.gautam@...eaurora.org> wrote:
> >
> > Hi Tomasz,
> >
> >
> > On 9/7/2018 2:46 PM, Tomasz Figa wrote:
> > > Hi Vivek,
> > >
> > > On Thu, Aug 30, 2018 at 11:46 PM Vivek Gautam
> > > <vivek.gautam@...eaurora.org> 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>
> > >> ---
> > >>   drivers/iommu/arm-smmu.c | 89 +++++++++++++++++++++++++++++++++++++++++++-----
> > >>   1 file changed, 81 insertions(+), 8 deletions(-)
> > > [snip]
> > >> @@ -2215,10 +2281,17 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
> > >>          if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
> > >>                  dev_err(&pdev->dev, "removing device with active domains!\n");
> > >>
> > >> +       arm_smmu_rpm_get(smmu);
> > >>          /* Turn the thing off */
> > >>          writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
> > >> +       arm_smmu_rpm_put(smmu);
> > >> +
> > >> +       if (pm_runtime_enabled(smmu->dev))
> > >> +               pm_runtime_force_suspend(smmu->dev);
> > >> +       else
> > >> +               clk_bulk_disable(smmu->num_clks, smmu->clks);
> > >>
> > >> -       clk_bulk_disable_unprepare(smmu->num_clks, smmu->clks);
> > >> +       clk_bulk_unprepare(smmu->num_clks, smmu->clks);
> > > Aren't we missing pm_runtime_disable() here? We'll have the enable
> > > count unbalanced if the driver is removed and probed again.
> >
> > pm_runtime_force_suspend() does a pm_runtime_disable() also if i am not
> > wrong.
> > And, as mentioned in a previous thread [1], we were seeing a warning
> > which we avoided
> > by keeping force_suspend().
> >
> > [1] https://lkml.org/lkml/2018/7/8/124
>
> I see, thanks. I didn't realize that pm_runtime_force_suspend()
> already disables runtime PM indeed. Sorry for the noise.

Hi Tomasz,
No problem. Thanks for looking back at it.

Hi Robin,
If you are fine with this series, then can you please consider giving
Reviewed-by, so that we are certain that this series will go in the next merge
window.
Thanks

Best regards
Vivek




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