From b3bad314cde3d5e3fcf1f966c542c8835656ae18 Mon Sep 17 00:00:00 2001 From: AngeloGioacchino Del Regno Date: Wed, 4 Aug 2021 16:39:35 +0200 Subject: [PATCH] iommu/arm-smmu-qcom: Allow choosing a custom bypass emulation context It cannot be taken for granted that the last IOMMU context is free and available for us to use it to emulate bypass streams and, at least on MSM8998's lpass iommu, using the last one will produce a crash; please note that this may not be only dependant on the SoC, but also on the firmware version. To overcome to this issue, allow specifying a different context for bypass emulation with the optional DT property "qcom,bypass-cbndx": if this property is not found this means that we are either booting with ACPI instead or that we don't want to specify a custom cb because the default one (the last context bank) is fine. Signed-off-by: AngeloGioacchino Del Regno --- drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index 55690af1b25d..c5fd20e68a2a 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -266,7 +266,8 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu) reg = arm_smmu_gr0_read(smmu, last_s2cr); if (FIELD_GET(ARM_SMMU_S2CR_TYPE, reg) != S2CR_TYPE_BYPASS) { qsmmu->bypass_quirk = true; - qsmmu->bypass_cbndx = smmu->num_context_banks - 1; + if (qsmmu->bypass_cbndx == 0xff) + qsmmu->bypass_cbndx = smmu->num_context_banks - 1; set_bit(qsmmu->bypass_cbndx, smmu->context_map); @@ -386,6 +387,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_impl = { static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu, const struct arm_smmu_impl *impl) { + const struct device_node *np = smmu->dev->of_node; struct qcom_smmu *qsmmu; /* Check to make sure qcom_scm has finished probing */ @@ -397,6 +399,16 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu, return ERR_PTR(-ENOMEM); qsmmu->smmu.impl = impl; + qsmmu->bypass_cbndx = 0xff; + + if (np != NULL) { + /* + * This property is optional and we expect to fail finding it if: + * - Using the default bypass_cbndx (in the .cfg_probe cb) is fine; or + * - We are booting on ACPI + */ + of_property_read_u8(np, "qcom,bypass-cbndx", &qsmmu->bypass_cbndx); + } return &qsmmu->smmu; }