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SubjectRe: [PATCH v9 3/5] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device
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Hi Robin,


On 3/14/2018 11:16 PM, Robin Murphy wrote:
> On 13/03/18 08:55, Vivek Gautam 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.
>>
>> 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>
>> ---
>>   drivers/iommu/arm-smmu.c | 95
>> ++++++++++++++++++++++++++++++++++++++++++++----
>>   1 file changed, 87 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index d5873d545024..56a04ae80bf3 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -268,6 +268,20 @@ static struct arm_smmu_option_prop
>> arm_smmu_options[] = {
>>       { 0, NULL},
>>   };
>>   +static inline int arm_smmu_rpm_get(struct arm_smmu_device *smmu)
>> +{
>> +    if (pm_runtime_enabled(smmu->dev))
>> +        return pm_runtime_get_sync(smmu->dev);
>> +
>> +    return 0;
>> +}
>> +
>> +static inline void arm_smmu_rpm_put(struct arm_smmu_device *smmu)
>> +{
>> +    if (pm_runtime_enabled(smmu->dev))
>> +        pm_runtime_put(smmu->dev);
>> +}
>> +
>>   static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain
>> *dom)
>>   {
>>       return container_of(dom, struct arm_smmu_domain, domain);
>> @@ -913,11 +927,15 @@ 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 = arm_smmu_rpm_get(smmu);
>> +    if (ret < 0)
>> +        return;
>> +
>>       /*
>>        * Disable the context bank and free the page tables before
>> freeing
>>        * it.
>> @@ -932,6 +950,8 @@ 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);
>> +
>> +    arm_smmu_rpm_put(smmu);
>>   }
>>     static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
>> @@ -1213,10 +1233,15 @@ static int arm_smmu_attach_dev(struct
>> iommu_domain *domain, struct device *dev)
>>           return -ENODEV;
>>         smmu = fwspec_smmu(fwspec);
>> +
>> +    ret = arm_smmu_rpm_get(smmu);
>> +    if (ret < 0)
>> +        return ret;
>> +
>>       /* Ensure that the domain is finalised */
>>       ret = arm_smmu_init_domain_context(domain, smmu);
>>       if (ret < 0)
>> -        return ret;
>> +        goto rpm_put;
>>         /*
>>        * Sanity check the domain. We don't support domains across
>> @@ -1230,29 +1255,47 @@ static int arm_smmu_attach_dev(struct
>> iommu_domain *domain, struct device *dev)
>>       }
>>         /* Looks ok, so add the device to the domain */
>> -    return arm_smmu_domain_add_master(smmu_domain, fwspec);
>> +    ret = arm_smmu_domain_add_master(smmu_domain, fwspec);
>> +
>> +rpm_put:
>> +    arm_smmu_rpm_put(smmu);
>> +    return ret;
>>   }
>>     static int arm_smmu_map(struct iommu_domain *domain, unsigned
>> long iova,
>>               phys_addr_t paddr, size_t size, int prot)
>>   {
>>       struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
>> +    struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +    struct arm_smmu_device *smmu = smmu_domain->smmu;
>
> Nit: please use arm_smmu_domain for ops as well (as it was before
> 523d7423e21b), or consistently elide it for smmu - the mixture of both
> methods is just a horrible mess (here and in unmap).

Sure, will make it consistent for arm_smmu_device (in both places -
map/unmap)

     struct arm_smmu_device *smmu = to_smmu_domain(domain)->smmu;

>
>> +    int ret;
>>         if (!ops)
>>           return -ENODEV;
>>   -    return ops->map(ops, iova, paddr, size, prot);
>> +    arm_smmu_rpm_get(smmu);
>> +    ret = ops->map(ops, iova, paddr, size, prot);
>> +    arm_smmu_rpm_put(smmu);
>> +
>> +    return ret;
>>   }
>>     static size_t arm_smmu_unmap(struct iommu_domain *domain,
>> unsigned long iova,
>>                    size_t size)
>>   {
>>       struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
>> +    struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +    struct arm_smmu_device *smmu = smmu_domain->smmu;
>> +    size_t ret;
>>         if (!ops)
>>           return 0;
>>   -    return ops->unmap(ops, iova, size);
>> +    arm_smmu_rpm_get(smmu);
>> +    ret = ops->unmap(ops, iova, size);
>> +    arm_smmu_rpm_put(smmu);
>> +
>> +    return ret;
>>   }
>>     static void arm_smmu_iotlb_sync(struct iommu_domain *domain)
>> @@ -1407,14 +1450,22 @@ static int arm_smmu_add_device(struct device
>> *dev)
>>       while (i--)
>>           cfg->smendx[i] = INVALID_SMENDX;
>>   +    ret = arm_smmu_rpm_get(smmu);
>> +    if (ret < 0)
>> +        goto out_cfg_free;
>> +
>>       ret = arm_smmu_master_alloc_smes(dev);
>
> Nit: it would be easier to just do the rpm_put here; then you don't
> need to mess with the cleanup path.

Sure, will do that. It will be cleaner.

>
>>       if (ret)
>> -        goto out_cfg_free;
>> +        goto out_rpm_put;
>>         iommu_device_link(&smmu->iommu, dev);
>>   +    arm_smmu_rpm_put(smmu);
>> +
>>       return 0;
>>   +out_rpm_put:
>> +    arm_smmu_rpm_put(smmu);
>>   out_cfg_free:
>>       kfree(cfg);
>>   out_free:
>> @@ -1427,7 +1478,7 @@ 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;
>> @@ -1435,8 +1486,15 @@ static void arm_smmu_remove_device(struct
>> device *dev)
>>       cfg  = fwspec->iommu_priv;
>>       smmu = cfg->smmu;
>>   +    ret = arm_smmu_rpm_get(smmu);
>> +    if (ret < 0)
>> +        return;
>> +
>>       iommu_device_unlink(&smmu->iommu, dev);
>>       arm_smmu_master_free_smes(fwspec);
>> +
>> +    arm_smmu_rpm_put(smmu);
>> +
>>       iommu_group_remove_device(dev);
>>       kfree(fwspec->iommu_priv);
>>       iommu_fwspec_free(dev);
>> @@ -2124,6 +2182,8 @@ static int arm_smmu_device_probe(struct
>> platform_device *pdev)
>>           smmu->irqs[i] = irq;
>>       }
>>   +    platform_set_drvdata(pdev, smmu);
>> +
>>       err = devm_clk_bulk_get(smmu->dev, smmu->num_clks, smmu->clks);
>>       if (err)
>>           return err;
>> @@ -2132,6 +2192,19 @@ 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);
>> +    if (err < 0)
>> +        return err;
>> +
>>       err = arm_smmu_device_cfg_probe(smmu);
>>       if (err)
>>           return err;
>> @@ -2173,10 +2246,11 @@ 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);
>>   +    arm_smmu_rpm_put(smmu);
>> +
>>       /*
>>        * For ACPI and generic DT bindings, an SMMU will be probed before
>>        * any device which might need it, so we want the bus ops in place
>> @@ -2212,8 +2286,13 @@ 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_disable(smmu->dev);
>>         clk_bulk_unprepare(smmu->num_clks, smmu->clks);
>
> I don't know how runtime and system PM interact - does the reset in
> arm_smmu_pm_resume need special treatment as well, or is the device
> guaranteed to be powered up at that point by other means?

So, as Tomasz wrote, we should be okay with this.
Thanks.

regards
Vivek
>
> Robin.
> --
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