Hi Robin,
On 1/31/2018 6:36 PM, Robin Murphy wrote:
> On 19/01/18 11:43, Vivek Gautam wrote:
>> From: Sricharan R <sricharan@xxxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxxxxxxx>
>> [vivek: Cleanup pm runtime calls]
>> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
>> ---
>> 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.
>> +
>> + 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.
Regards,
Sricharan
--
"QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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