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From:   Vivek Gautam <vivek.gautam@codeaurora.org>
Date:   Tue, 18 Sep 2018 08:41:41 +0530
Message-ID: <CAFp+6iHnHj_PkPFBUSTdJTW57K51wLqSEw6VOMKxAVo7O+ms9g@mail.gmail.com>
Subject: Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm_runtime during probe,
 add/remove device
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     Mark Rutland <mark.rutland@arm.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, alex.williamson@redhat.com,
        Linux PM <linux-pm@vger.kernel.org>, sboyd@kernel.org,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Will Deacon <will.deacon@arm.com>,
        open list <linux-kernel@vger.kernel.org>,
        "list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>, Joerg
        Roedel <joro@8bytes.org>," <iommu@lists.linux-foundation.org>,
        "robh+dt" <robh+dt@kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        freedreno <freedreno@lists.freedesktop.org>,
        Tomasz Figa <tfiga@chromium.org>
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Hi Robin,

On Fri, Sep 7, 2018 at 3:52 PM Vivek Gautam <vivek.gautam@codeaurora.org> wrote:
>
> On Fri, Sep 7, 2018 at 3:22 PM Tomasz Figa <tfiga@chromium.org> wrote:
> >
> > On Fri, Sep 7, 2018 at 6:38 PM Vivek Gautam <vivek.gautam@codeaurora.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@codeaurora.org> wrote:
> > > >> From: Sricharan R <sricharan@codeaurora.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@codeaurora.org>
> > > >> [vivek: Cleanup pm runtime calls]
> > > >> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> > > >> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> > > >> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.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

Gentle ping.
You ack will be very helpful in letting Will pull this series for 4.20.
Thanks.

Best regards
Vivek


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