Message-ID: <1568773.GtDhb2pIXv@aspire.rjw.lan>
Date:   Tue, 09 Jan 2018 12:23:23 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     joro@...tes.org, robh+dt@...nel.org, mark.rutland@....com,
        gregkh@...uxfoundation.org, robdclark@...il.com,
        will.deacon@....com, robin.murphy@....com, sboyd@...eaurora.org,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        len.brown@...el.com, pavel@....cz, airlied@...ux.ie,
        sricharan@...eaurora.org, m.szyprowski@...sung.com,
        architt@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v5 0/6] iommu/arm-smmu: Add runtime pm/sleep support

On Tuesday, January 9, 2018 11:01:43 AM CET Vivek Gautam wrote:
> This series provides the support for turning on the arm-smmu's
> clocks/power domains using runtime pm. This is done using the
> recently introduced device links patches, which lets the smmu's
> runtime to follow the master's runtime pm, so the smmu remains
> powered only when the masters use it.
> 
> It also adds support for Qcom's arm-smmu-v2 variant that
> has different clocks and power requirements.
> 
> Took some reference from the exynos runtime patches [2].
> 
> Previous version of the patchset [1].
> 
> After much discussion [4] over the use of pm_runtime_get/put() in
> .unmap op path for the arm-smmu, and after disussing over more than
> a couple of approaches to address this, we are putting forward the
> changes *without* using pm_runtime APIs in 'unmap'. Rather, letting
> the client device take the control of powering on/off the connected
> iommu through pm_runtime_get(put)_suppliers() APIs for the scnerios
> when the iommu power can't be directly controlled by clients through
> device links.
> Rafael has agreed to export the suppliers APIs [5].
> 
> [V5]
>    * Dropped runtime pm calls from "arm_smmu_unmap" op as discussed over
>      the list [4] for the last patch series.
>    * Added a patch to export pm_runtime_get/put_suppliers() APIs to the
>      series as agreed with Rafael [5].
>    * Added the related patch for msm drm iommu layer to use
>      pm_runtime_get/put_suppliers() APIs in msm_mmu_funcs.
>    * Dropped arm-mmu500 clock patch since that would break existing
>      platforms.
>    * Changed compatible 'qcom,msm8996-smmu-v2' to 'qcom,smmu-v2' to reflect
>      the IP version rather than the platform on which it is used.
>      The same IP is used across multiple platforms including msm8996,
>      and sdm845 etc.
>    * Using clock bulk APIs to handle the clocks available to the IP as
>      suggested by Stephen Boyd.
>    * The first patch in v4 version of the patch-series:
>      ("iommu/arm-smmu: Fix the error path in arm_smmu_add_device") has
>      already made it to mainline.
> 
> [V4]
>    * Reworked the clock handling part. We now take clock names as data
>      in the driver for supported compatible versions, and loop over them
>      to get, enable, and disable the clocks.
>    * Using qcom,msm8996 based compatibles for bindings instead of a generic
>      qcom compatible.
>    * Refactor MMU500 patch to just add the necessary clock names data and
>      corresponding bindings.
>    * Added the pm_runtime_get/put() calls in .unmap iommu op (fix added by
>      Stanimir on top of previous patch version.
>    * Added a patch to fix error path in arm_smmu_add_device()
>    * Removed patch 3/5 of V3 patch series that added qcom,smmu-v2 bindings.
> 
> [V3]
>    * Reworked the patches to keep the clocks init/enabling function
>      separately for each compatible.
> 
>    * Added clocks bindings for MMU40x/500.
> 
>    * Added a new compatible for qcom,smmu-v2 implementation and
>      the clock bindings for the same.
> 
>    * Rebased on top of 4.11-rc1
> 
> [V2]
>    * Split the patches little differently.
> 
>    * Addressed comments.
> 
>    * Removed the patch #4 [3] from previous post
>      for arm-smmu context save restore. Planning to
>      post this separately after reworking/addressing Robin's
>      feedback.
> 
>    * Reversed the sequence to disable clocks than enabling.
>      This was required for those cases where the
>      clocks are populated in a dependent order from DT.
> 
> [1] https://www.spinics.net/lists/arm-kernel/msg567488.html
> [2] https://lkml.org/lkml/2016/10/20/70
> [3] https://patchwork.kernel.org/patch/9389717/
> [4] https://patchwork.kernel.org/patch/9827825/
> [5] https://patchwork.kernel.org/patch/10102445/
> 
> Sricharan R (3):
>   iommu/arm-smmu: Add pm_runtime/sleep ops
>   iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device
>   iommu/arm-smmu: Add the device_link between masters and smmu
> 
> Vivek Gautam (3):
>   base: power: runtime: Export pm_runtime_get/put_suppliers
>   iommu/arm-smmu: Add support for qcom,smmu-v2 variant
>   drm/msm: iommu: Replace runtime calls with runtime suppliers
> 
>  .../devicetree/bindings/iommu/arm,smmu.txt         |  35 ++++++
>  drivers/base/power/runtime.c                       |   2 +
>  drivers/gpu/drm/msm/msm_iommu.c                    |  16 +--
>  drivers/iommu/arm-smmu.c                           | 124 ++++++++++++++++++++-
>  4 files changed, 163 insertions(+), 14 deletions(-)

I need some time to review the series.

Thanks,
Rafael

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