linux-kernel - Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device

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Date:   Thu, 13 Jul 2017 11:05:59 +0530
From:   Sricharan R <sricharan@...eaurora.org>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     joro@...tes.org, robin.murphy@....com, robh+dt@...nel.org,
        mark.rutland@....com, will.deacon@....com,
        m.szyprowski@...sung.com, robdclark@...il.com,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, stanimir.varbanov@...aro.org,
        architt@...eaurora.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V4 3/6] iommu/arm-smmu: Invoke pm_runtime during probe,
 add/remove device

Hi Vivek,

On 7/13/2017 10:43 AM, Vivek Gautam wrote:
> Hi Stephen,
> 
> 
> On 07/13/2017 04:24 AM, Stephen Boyd wrote:
>> On 07/06, Vivek Gautam wrote:
>>> @@ -1231,12 +1237,18 @@ static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
>>>   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 io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
>>> +    size_t ret;
>>>         if (!ops)
>>>           return 0;
>>>   -    return ops->unmap(ops, iova, size);
>>> +    pm_runtime_get_sync(smmu_domain->smmu->dev);
>> Can these map/unmap ops be called from an atomic context? I seem
>> to recall that being a problem before.
> 
> That's something which was dropped in the following patch merged in master:
> 523d7423e21b iommu/arm-smmu: Remove io-pgtable spinlock
> 
> Looks like we don't  need locks here anymore?

 Apart from the locking, wonder why a explicit pm_runtime is needed
 from unmap. Somehow looks like some path in the master using that
 should have enabled the pm ?

Regards,
 Sricharan

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