linux-kernel - [PATCH 3/3] iommu/arm-smmu: re-enable context caching in smmu reset operation

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Date:   Sat, 4 Nov 2023 03:21:24 +0530
From:   Bibek Kumar Patro <quic_bibekkum@...cinc.com>
To:     <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
        <dmitry.baryshkov@...aro.org>, <a39.skl@...il.com>,
        <konrad.dybcio@...aro.org>, <quic_saipraka@...cinc.com>,
        <quic_pkondeti@...cinc.com>, <quic_molvera@...cinc.com>
CC:     <linux-arm-kernel@...ts.infradead.org>, <iommu@...ts.linux.dev>,
        <linux-kernel@...r.kernel.org>, <qipl.kernel.upstream@...cinc.com>,
        "Bibek Kumar Patro" <quic_bibekkum@...cinc.com>
Subject: [PATCH 3/3] iommu/arm-smmu: re-enable context caching in smmu reset operation

Context caching is re-enabled in the prefetch buffer for Qualcomm SoCs
through SoC specific reset ops, which is disabled in the default MMU-500
reset ops, but is expected for context banks using ACTLR register to
retain the prefetch value during reset and runtime suspend.

Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 26 ++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 590b7c285299..f342b4778cf1 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -457,11 +457,29 @@ static int qcom_smmu_def_domain_type(struct device *dev)
 	return match ? IOMMU_DOMAIN_IDENTITY : 0;
 }

+#define ARM_MMU500_ACTLR_CPRE          BIT(1)
+
+static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
+{
+	int i;
+	u32 reg;
+
+	arm_mmu500_reset(smmu);
+
+		for (i = 0; i < smmu->num_context_banks; ++i) {
+			reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
+			reg |= ARM_MMU500_ACTLR_CPRE;
+			arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg);
+		}
+
+	return 0;
+}
+
 static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
 {
 	int ret;

-	arm_mmu500_reset(smmu);
+	qcom_smmu500_reset(smmu);

 	/*
 	 * To address performance degradation in non-real time clients,
@@ -488,7 +506,7 @@ static const struct arm_smmu_impl qcom_smmu_500_impl = {
 	.init_context = qcom_smmu_init_context,
 	.cfg_probe = qcom_smmu_cfg_probe,
 	.def_domain_type = qcom_smmu_def_domain_type,
-	.reset = arm_mmu500_reset,
+	.reset = qcom_smmu500_reset,
 	.write_s2cr = qcom_smmu_write_s2cr,
 	.tlb_sync = qcom_smmu_tlb_sync,
 };
@@ -507,7 +525,7 @@ static const struct arm_smmu_impl sm8550_smmu_500_impl = {
 	.init_context = qcom_smmu_init_context,
 	.cfg_probe = qcom_smmu_cfg_probe,
 	.def_domain_type = qcom_smmu_def_domain_type,
-	.reset = arm_mmu500_reset,
+	.reset = qcom_smmu500_reset,
 	.write_s2cr = qcom_smmu_write_s2cr,
 	.tlb_sync = qcom_smmu_tlb_sync,
 };
@@ -523,7 +541,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_v2_impl = {
 static const struct arm_smmu_impl qcom_adreno_smmu_500_impl = {
 	.init_context = qcom_adreno_smmu_init_context,
 	.def_domain_type = qcom_smmu_def_domain_type,
-	.reset = arm_mmu500_reset,
+	.reset = qcom_smmu500_reset,
 	.alloc_context_bank = qcom_adreno_smmu_alloc_context_bank,
 	.write_sctlr = qcom_adreno_smmu_write_sctlr,
 	.tlb_sync = qcom_smmu_tlb_sync,
--
2.17.1