Re: [PATCH 1/5] drm/msm: Remove pm_runtime operations from msm_iommu

From: Vivek Gautam <vivek.gautam-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
To: Jordan Crouse <jcrouse-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Cc: linux-arm-msm
	<linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	freedreno
	<freedreno-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	dri-devel
	<dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>
Subject: Re: [PATCH 1/5] drm/msm: Remove pm_runtime operations from msm_iommu
Date: Thu, 14 Jun 2018 12:30:35 +0530	[thread overview]
Message-ID: <CAFp+6iGoub2V3Cb2kXJ0GDd2t4qRPZBf+YM8HYN9gn2DtCm+4Q@mail.gmail.com> (raw)
In-Reply-To: <20180611182604.30467-2-jcrouse-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

Hi Jordan,

On Mon, Jun 11, 2018 at 11:56 PM, Jordan Crouse <jcrouse@codeaurora.org> wrote:
> Now that the IOMMU is the master of it's own power we don't need to bring
> up the GPU to do IOMMU operations. This is good because bringing up a6xx
> requires the GMU so calling pm_runtime_get_sync() too early in the process
> gets us into some nasty circular dependency situations.

Thanks for the patch.
While you are removing these calls, we should add pm_runtime calls
to qcom_iommu_map(). That should make qcom_iommu too master of
its power control.
Then we should be good to go with this patch.

>
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/msm_iommu.c | 8 --------
>  1 file changed, 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index b23d33622f37..ccd93ac6a4d8 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -40,9 +40,7 @@ static int msm_iommu_attach(struct msm_mmu *mmu, const char * const *names,
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>         int ret;
>
> -       pm_runtime_get_sync(mmu->dev);
>         ret = iommu_attach_device(iommu->domain, mmu->dev);
> -       pm_runtime_put_sync(mmu->dev);

may be just do the following here.
           return iommu_attach_device(iommu->domain, mmu->dev);

Rest looks good. So after the change.
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>

Best regards
Vivek

>
>         return ret;
>  }
> @@ -52,9 +50,7 @@ static void msm_iommu_detach(struct msm_mmu *mmu, const char * const *names,
>  {
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>
> -       pm_runtime_get_sync(mmu->dev);
>         iommu_detach_device(iommu->domain, mmu->dev);
> -       pm_runtime_put_sync(mmu->dev);
>  }
>
>  static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
> @@ -63,9 +59,7 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>         size_t ret;
>
> -//     pm_runtime_get_sync(mmu->dev);
>         ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot);
> -//     pm_runtime_put_sync(mmu->dev);
>         WARN_ON(ret < 0);
>
>         return (ret == len) ? 0 : -EINVAL;
> @@ -76,9 +70,7 @@ static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova,
>  {
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>
> -       pm_runtime_get_sync(mmu->dev);
>         iommu_unmap(iommu->domain, iova, len);
> -       pm_runtime_put_sync(mmu->dev);
>
>         return 0;
>  }
> --
> 2.17.1
>
> --
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