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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id r7sm6211950pgu.51.2020.07.16.17.16.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jul 2020 17:16:24 -0700 (PDT) From: Bjorn Andersson To: Will Deacon , Robin Murphy , Joerg Roedel , Thierry Reding , Laurentiu Tudor Cc: linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jonathan Marek , linux-arm-msm@vger.kernel.org, John Stultz , Vinod Koul Subject: [PATCH v2 2/5] iommu/arm-smmu: Emulate bypass by using context banks Date: Thu, 16 Jul 2020 17:16:16 -0700 Message-Id: <20200717001619.325317-3-bjorn.andersson@linaro.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200717001619.325317-1-bjorn.andersson@linaro.org> References: <20200717001619.325317-1-bjorn.andersson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some firmware found on various Qualcomm platforms traps writes to S2CR of type BYPASS and writes FAULT into the register. This prevents us from marking the streams for the display controller as BYPASS to allow continued scanout of the screen through the initialization of the ARM SMMU. This adds a Qualcomm specific cfg_probe function, which probes the behavior of the S2CR registers and if found faulty enables the related quirk. Based on this quirk context banks are allocated for IDENTITY domains as well, but with ARM_SMMU_SCTLR_M omitted. The result is valid stream mappings, without translation. Tested-by: John Stultz Tested-by: Vinod Koul Signed-off-by: Bjorn Andersson --- Changes since v1: - Picked up tested-by drivers/iommu/arm-smmu-qcom.c | 21 +++++++++++++++++++++ drivers/iommu/arm-smmu.c | 14 ++++++++++++-- drivers/iommu/arm-smmu.h | 3 +++ 3 files changed, 36 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c index be4318044f96..d95a5ee8c83c 100644 --- a/drivers/iommu/arm-smmu-qcom.c +++ b/drivers/iommu/arm-smmu-qcom.c @@ -23,6 +23,26 @@ static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = { { } }; +static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu) +{ + unsigned int last_s2cr = ARM_SMMU_GR0_S2CR(smmu->num_mapping_groups - 1); + u32 reg; + + /* + * With some firmware writes to S2CR of type FAULT are ignored, and + * writing BYPASS will end up as FAULT in the register. Perform a write + * to S2CR to detect if this is the case with the current firmware. + */ + arm_smmu_gr0_write(smmu, last_s2cr, FIELD_PREP(ARM_SMMU_S2CR_TYPE, S2CR_TYPE_BYPASS) | + FIELD_PREP(ARM_SMMU_S2CR_CBNDX, 0xff) | + FIELD_PREP(ARM_SMMU_S2CR_PRIVCFG, S2CR_PRIVCFG_DEFAULT)); + reg = arm_smmu_gr0_read(smmu, last_s2cr); + if (FIELD_GET(ARM_SMMU_S2CR_TYPE, reg) != S2CR_TYPE_BYPASS) + smmu->qcom_bypass_quirk = true; + + return 0; +} + static int qcom_smmu_def_domain_type(struct device *dev) { const struct of_device_id *match = @@ -61,6 +81,7 @@ static int qcom_smmu500_reset(struct arm_smmu_device *smmu) } static const struct arm_smmu_impl qcom_smmu_impl = { + .cfg_probe = qcom_smmu_cfg_probe, .def_domain_type = qcom_smmu_def_domain_type, .reset = qcom_smmu500_reset, }; diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index fb85e716ae9a..5d5fe6741ed4 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -654,7 +654,9 @@ static void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx) /* SCTLR */ reg = ARM_SMMU_SCTLR_CFIE | ARM_SMMU_SCTLR_CFRE | ARM_SMMU_SCTLR_AFE | - ARM_SMMU_SCTLR_TRE | ARM_SMMU_SCTLR_M; + ARM_SMMU_SCTLR_TRE; + if (cfg->m) + reg |= ARM_SMMU_SCTLR_M; if (stage1) reg |= ARM_SMMU_SCTLR_S1_ASIDPNE; if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) @@ -678,7 +680,11 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, if (smmu_domain->smmu) goto out_unlock; - if (domain->type == IOMMU_DOMAIN_IDENTITY) { + /* + * Nothing to do for IDENTITY domains,unless disabled context banks are + * used to emulate bypass mappings on Qualcomm platforms. + */ + if (domain->type == IOMMU_DOMAIN_IDENTITY && !smmu->qcom_bypass_quirk) { smmu_domain->stage = ARM_SMMU_DOMAIN_BYPASS; smmu_domain->smmu = smmu; goto out_unlock; @@ -826,6 +832,10 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, domain->geometry.aperture_end = (1UL << ias) - 1; domain->geometry.force_aperture = true; + /* Enable translation for non-identity context banks */ + if (domain->type != IOMMU_DOMAIN_IDENTITY) + cfg->m = true; + /* Initialise the context bank with our page table cfg */ arm_smmu_init_context_bank(smmu_domain, &pgtbl_cfg); arm_smmu_write_context_bank(smmu, cfg->cbndx); diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h index d172c024be61..a71d193073e4 100644 --- a/drivers/iommu/arm-smmu.h +++ b/drivers/iommu/arm-smmu.h @@ -305,6 +305,8 @@ struct arm_smmu_device { /* IOMMU core code handle */ struct iommu_device iommu; + + bool qcom_bypass_quirk; }; enum arm_smmu_context_fmt { @@ -323,6 +325,7 @@ struct arm_smmu_cfg { }; enum arm_smmu_cbar_type cbar; enum arm_smmu_context_fmt fmt; + bool m; }; #define ARM_SMMU_INVALID_IRPTNDX 0xff -- 2.26.2