linux-kernel - [PATCH v3 4/4] iommu/arm-smmu: re-enable context caching in smmu reset operation

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Message-ID: <20231127145412.3981-5-quic_bibekkum@quicinc.com>
Date:   Mon, 27 Nov 2023 20:24:12 +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_bjorande@...cinc.com>,
        <mani@...nel.org>, <quic_eberman@...cinc.com>,
        <robdclark@...omium.org>, <u.kleine-koenig@...gutronix.de>,
        <robh@...nel.org>, <vladimir.oltean@....com>,
        <quic_pkondeti@...cinc.com>, <quic_molvera@...cinc.com>
CC:     <linux-arm-msm@...r.kernel.org>,
        <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 v3 4/4] iommu/arm-smmu: re-enable context caching in smmu reset operation

Default MMU-500 reset operation disables context caching in
prefetch buffer. It is however expected for context banks using
the ACTLR register to retain their prefetch value during reset
and runtime suspend.

Replace default MMU-500 reset operation with Qualcomm specific reset
operation which envelope the default reset operation and re-enables
context caching in prefetch buffer for Qualcomm SoCs.

Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 23 +++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index f0ad09f9a974..2c676a09fa31 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -512,11 +512,28 @@ static int qcom_smmu_def_domain_type(struct device *dev)
 	return match ? IOMMU_DOMAIN_IDENTITY : 0;
 }

+static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
+{
+	int i;
+	u32 reg;
+
+	arm_mmu500_reset(smmu);
+
+	/* Re-enable context caching after reset */
+	for (i = 0; i < smmu->num_context_banks; ++i) {
+		reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
+		reg |= 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,
@@ -543,7 +560,7 @@ 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,
 };
@@ -568,7 +585,7 @@ 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