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Date:   Tue, 10 Aug 2021 12:18:08 +0530
From:   Sai Prakash Ranjan <>
To:     Will Deacon <>, Robin Murphy <>,
        Joerg Roedel <>
Cc:,,,, Taniya Das <>,
        Rob Clark <>,
        Sai Prakash Ranjan <>,
        Rajendra Nayak <>
Subject: [PATCHv2] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks

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.

This is a similar sequence of clock requests (prepare,enable and
disable,unprepare) in arm-smmu probe and remove.

Signed-off-by: Sai Prakash Ranjan <>
Co-developed-by: Rajendra Nayak <>
Signed-off-by: Rajendra Nayak <>

Changes in v2:
 * Add clk unprepare when clk enable fails in resume (Will)

 drivers/iommu/arm/arm-smmu/arm-smmu.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index d3c6f54110a5..da8ef9d82d79 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -2277,18 +2277,38 @@ static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
 static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
+	int ret;
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+	ret = clk_bulk_prepare(smmu->num_clks, smmu->clks);
+	if (ret)
+		return ret;
 	if (pm_runtime_suspended(dev))
 		return 0;
-	return arm_smmu_runtime_resume(dev);
+	ret = arm_smmu_runtime_resume(dev);
+	if (ret)
+		clk_bulk_unprepare(smmu->num_clks, smmu->clks);
+	return ret;
 static int __maybe_unused arm_smmu_pm_suspend(struct device *dev)
+	int ret = 0;
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
 	if (pm_runtime_suspended(dev))
-		return 0;
+		goto clk_unprepare;
-	return arm_smmu_runtime_suspend(dev);
+	ret = arm_smmu_runtime_suspend(dev);
+	if (ret)
+		return ret;
+	clk_bulk_unprepare(smmu->num_clks, smmu->clks);
+	return ret;
 static const struct dev_pm_ops arm_smmu_pm_ops = {
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