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Date: Thu, 30 Aug 2018 18:33:53 +0900 From: Tomasz Figa <tfiga@...omium.org> To: Vivek Gautam <vivek.gautam@...eaurora.org> Cc: "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg Roedel <joro@...tes.org>," <joro@...tes.org>, Rob Herring <robh+dt@...nel.org>, Robin Murphy <robin.murphy@....com>, Will Deacon <will.deacon@....com>, "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg Roedel <joro@...tes.org>," <iommu@...ts.linux-foundation.org>, devicetree@...r.kernel.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, freedreno <freedreno@...ts.freedesktop.org>, Mark Rutland <mark.rutland@....com>, Linux PM <linux-pm@...r.kernel.org>, sboyd@...nel.org, linux-arm-msm <linux-arm-msm@...r.kernel.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Alex Williamson <alex.williamson@...hat.com>, Andy Gross <andy.gross@...aro.org> Subject: Re: [Patch v15 2/5] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device On Thu, Aug 30, 2018 at 6:22 PM Vivek Gautam <vivek.gautam@...eaurora.org> wrote: > > On Mon, Aug 27, 2018 at 4:27 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. > > > > 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> > > --- > > > > Changes since v14: > > - none. > > > > drivers/iommu/arm-smmu.c | 101 +++++++++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 93 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > > index a81224bc6637..23b4a60149b6 100644 > > --- a/drivers/iommu/arm-smmu.c > > +++ b/drivers/iommu/arm-smmu.c > > [snip] > > > @@ -2131,6 +2188,26 @@ static int arm_smmu_device_probe(struct platform_device *pdev) > > if (err) > > return err; > > > > + /* > > + * We want to avoid touching dev->power.lock in fastpaths unless > > + * it's really going to do something useful - pm_runtime_enabled() > > + * can serve as an ideal proxy for that decision. So, conditionally > > + * enable pm_runtime. > > + */ > > + if (dev->pm_domain) > > + pm_runtime_enable(dev); > > + > > + err = arm_smmu_rpm_get(smmu); > > We shouldn't be doing a runtime_get() yet, as this eventually calls > arm_smmu_device_reset(). > arm_smmu_device_reset() should be called only after arm_smmu_device_cfg_probe(). > So, I plan to replace the pm_runtime_get/put() calls in probe() with > simple clk_bulk_enable() > to let the driver initialize smmu, and at the end of the probe we can > disable the clocks and > enable runtime pm over the device to let it take care of the device further-on. > We can avoid the explicit clock disable by just calling pm_runtime_set_active() before pm_runtime_enable(), assuming that what probe does is symmetrical with the suspend callback, which would be called after the latter. Best regards, Tomasz
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