linux-kernel - Re: [PATCHv2] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks

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Date:   Tue, 10 Aug 2021 21:25:55 +0100
From:   Will Deacon <will@...nel.org>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Joerg Roedel <joro@...tes.org>,
        Robin Murphy <robin.murphy@....com>
Cc:     catalin.marinas@....com, kernel-team@...roid.com,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Rob Clark <robdclark@...il.com>,
        Taniya Das <tdas@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks

On Tue, 10 Aug 2021 12:18:08 +0530, Sai Prakash Ranjan wrote:
> Some clocks for SMMU can have parent as XO such as gpu_cc_hub_cx_int_clk
> of GPU SMMU in QTI SC7280 SoC and in order to enter deep sleep states in
> such cases, we would need to drop the XO clock vote in unprepare call and
> this unprepare callback for XO is in RPMh (Resource Power Manager-Hardened)
> clock driver which controls RPMh managed clock resources for new QTI SoCs.
> 
> Given we cannot have a sleeping calls such as clk_bulk_prepare() and
> clk_bulk_unprepare() in arm-smmu runtime pm callbacks since the iommu
> operations like map and unmap can be in atomic context and are in fast
> path, add this prepare and unprepare call to drop the XO vote only for
> system pm callbacks since it is not a fast path and we expect the system
> to enter deep sleep states with system pm as opposed to runtime pm.
> 
> [...]

Applied to will (for-joerg/arm-smmu/updates), thanks!

[1/1] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks
      https://git.kernel.org/will/c/afefe67e0893

Cheers,
-- 
Will

https://fixes.arm64.dev
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