linux-kernel - Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm

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Date:   Wed, 21 Nov 2018 17:37:57 +0000
From:   Will Deacon <will.deacon@....com>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     joro@...tes.org, robh+dt@...nel.org, robin.murphy@....com,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        mark.rutland@....com, rjw@...ysocki.net, robdclark@...il.com,
        linux-pm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        sboyd@...nel.org, tfiga@...omium.org, jcrouse@...eaurora.org,
        sricharan@...eaurora.org, m.szyprowski@...sung.com,
        architt@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm_runtime during
 probe, add/remove device

On Fri, Nov 16, 2018 at 04:54:27PM +0530, Vivek Gautam 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.
> Global locks are also initialized before enabling runtime pm as the
> runtime_resume() calls device_reset() which does tlb_sync_global()
> that ultimately requires locks to be initialized.
> 
> 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>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> ---
>  drivers/iommu/arm-smmu.c | 101 ++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 91 insertions(+), 10 deletions(-)

Given that you're doing the get/put in the TLBI ops unconditionally:

>  static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain)
>  {
>  	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> +	struct arm_smmu_device *smmu = smmu_domain->smmu;
>  
> -	if (smmu_domain->tlb_ops)
> +	if (smmu_domain->tlb_ops) {
> +		arm_smmu_rpm_get(smmu);
>  		smmu_domain->tlb_ops->tlb_flush_all(smmu_domain);
> +		arm_smmu_rpm_put(smmu);
> +	}
>  }
>  
>  static void arm_smmu_iotlb_sync(struct iommu_domain *domain)
>  {
>  	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> +	struct arm_smmu_device *smmu = smmu_domain->smmu;
>  
> -	if (smmu_domain->tlb_ops)
> +	if (smmu_domain->tlb_ops) {
> +		arm_smmu_rpm_get(smmu);
>  		smmu_domain->tlb_ops->tlb_sync(smmu_domain);
> +		arm_smmu_rpm_put(smmu);
> +	}

Why do you need them around the map/unmap calls as well?

Will