From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Gautam Subject: Re: [PATCH v6 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device Date: Thu, 1 Feb 2018 18:01:54 +0530 Message-ID: References: <1516362223-22946-1-git-send-email-vivek.gautam@codeaurora.org> <1516362223-22946-4-git-send-email-vivek.gautam@codeaurora.org> <5367e45a-8406-6dd2-1eb8-e1de9095af1a@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sricharan R , Robin Murphy , alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, freedreno-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, architt-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: dri-devel@lists.freedesktop.org On 2/1/2018 5:03 PM, Sricharan R wrote: > Hi Robin, > > On 1/31/2018 6:36 PM, Robin Murphy wrote: >> On 19/01/18 11:43, Vivek Gautam wrote: >>> From: Sricharan R >>> >>> 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 >>> [vivek: Cleanup pm runtime calls] >>> Signed-off-by: Vivek Gautam >>> --- >>>   drivers/iommu/arm-smmu.c | 45 +++++++++++++++++++++++++++++++++++++++++---- >>>   1 file changed, 41 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >>> index 21acffe91a1c..95478bfb182c 100644 >>> --- a/drivers/iommu/arm-smmu.c >>> +++ b/drivers/iommu/arm-smmu.c >>> @@ -914,11 +914,15 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) >>>       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); >>>       struct arm_smmu_device *smmu = smmu_domain->smmu; >>>       struct arm_smmu_cfg *cfg = &smmu_domain->cfg; >>> -    int irq; >>> +    int ret, irq; >>>         if (!smmu || domain->type == IOMMU_DOMAIN_IDENTITY) >>>           return; >>>   +    ret = pm_runtime_get_sync(smmu->dev); >>> +    if (ret) >>> +        return; >>> + >>>       /* >>>        * Disable the context bank and free the page tables before freeing >>>        * it. >>> @@ -933,6 +937,8 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) >>>         free_io_pgtable_ops(smmu_domain->pgtbl_ops); >>>       __arm_smmu_free_bitmap(smmu->context_map, cfg->cbndx); >>> + >>> +    pm_runtime_put_sync(smmu->dev); >>>   } >>>     static struct iommu_domain *arm_smmu_domain_alloc(unsigned type) >>> @@ -1408,12 +1414,20 @@ static int arm_smmu_add_device(struct device *dev) >>>       while (i--) >>>           cfg->smendx[i] = INVALID_SMENDX; >>>   -    ret = arm_smmu_master_alloc_smes(dev); >>> +    ret = pm_runtime_get_sync(smmu->dev); >>>       if (ret) >>>           goto out_cfg_free; >>>   +    ret = arm_smmu_master_alloc_smes(dev); >>> +    if (ret) { >>> +        pm_runtime_put_sync(smmu->dev); >>> +        goto out_cfg_free; >> Please keep to the existing pattern and put this on the cleanup path with a new label, rather than inline. > ok. > >>> +    } >>> + >>>       iommu_device_link(&smmu->iommu, dev); >>>   +    pm_runtime_put_sync(smmu->dev); >>> + >>>       return 0; >>>     out_cfg_free: >>> @@ -1428,7 +1442,7 @@ static void arm_smmu_remove_device(struct device *dev) >>>       struct iommu_fwspec *fwspec = dev->iommu_fwspec; >>>       struct arm_smmu_master_cfg *cfg; >>>       struct arm_smmu_device *smmu; >>> - >>> +    int ret; >>>         if (!fwspec || fwspec->ops != &arm_smmu_ops) >>>           return; >>> @@ -1436,8 +1450,21 @@ static void arm_smmu_remove_device(struct device *dev) >>>       cfg  = fwspec->iommu_priv; >>>       smmu = cfg->smmu; >>>   +    /* >>> +     * The device link between the master device and >>> +     * smmu is already purged at this point. >>> +     * So enable the power to smmu explicitly. >>> +     */ >> I don't understand this comment, especially since we don't even introduce device links until the following patch... :/ >> > This is because the core device_del callback, does a device_links_purge for that device, > before calling the remove_device notifier. As a result, have to explicitly turn on the > power to iommu. Probably the comment should be removed, rest of the places we don't > explain why we are turning on explicitly. Yes, will remove the comment here. > >>> + >>> +    ret = pm_runtime_get_sync(smmu->dev); >>> +    if (ret) >>> +        return; >>> + >>>       iommu_device_unlink(&smmu->iommu, dev); >>>       arm_smmu_master_free_smes(fwspec); >>> + >>> +    pm_runtime_put_sync(smmu->dev); >>> + >>>       iommu_group_remove_device(dev); >>>       kfree(fwspec->iommu_priv); >>>       iommu_fwspec_free(dev); >>> @@ -2130,6 +2157,14 @@ static int arm_smmu_device_probe(struct platform_device *pdev) >>>       if (err) >>>           return err; >>>   +    platform_set_drvdata(pdev, smmu); >>> + >>> +    pm_runtime_enable(dev); >>> + >>> +    err = pm_runtime_get_sync(dev); >>> +    if (err) >>> +        return err; >>> + >>>       err = arm_smmu_device_cfg_probe(smmu); >>>       if (err) >>>           return err; >>> @@ -2171,9 +2206,9 @@ static int arm_smmu_device_probe(struct platform_device *pdev) >>>           return err; >>>       } >>>   -    platform_set_drvdata(pdev, smmu); >>>       arm_smmu_device_reset(smmu); >>>       arm_smmu_test_smr_masks(smmu); >>> +    pm_runtime_put_sync(dev); >>>         /* >>>        * For ACPI and generic DT bindings, an SMMU will be probed before >>> @@ -2212,6 +2247,8 @@ static int arm_smmu_device_remove(struct platform_device *pdev) >>>         /* Turn the thing off */ >>>       writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0); >>> +    pm_runtime_force_suspend(smmu->dev); >> Why do we need this? I guess it might be a Qualcomm-ism as I don't see anyone else calling it from .remove other than a couple of other qcom_* drivers. Given that we only get here during system shutdown (or the root user intentionally pissing about with driver unbinding), it doesn't seem like a point where power saving really matters all that much. >> >> I'd also naively expect that anything this device was the last consumer off would get turned off by core code anyway once it's removed, but maybe things aren't that slick; I dunno :/ > hmm, that should not be needed. with turning of all consumers taken care by device_link code before > the supplier (iommu) remove gets called should ensure that. So the above force_suspend should > not be needed/can be removed. But one more thing is, we do touch the register in the above code. > So that should require a additional get/put sync around that writel. Possibly we can replace the force_suspend() with a pm_runtime_disable() to complement pm_runtime_enable in the probe. I will test the scenario where we are writing the SMMU register in .remove path. regards Vivek > > Regards, > Sricharan > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html