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authorVivek Gautam <vivek.gautam@codeaurora.org>2019-09-20 13:34:29 +0530
committerWill Deacon <will@kernel.org>2019-11-04 17:48:37 +0000
commit759aaa10c76cbaaefc0670410fb2d54cf4ec10cc (patch)
treecf9af4fcdc4f84bdf37f34249efe4e71ef7156e0 /drivers/iommu
parent5eb0e0e4f90addc6b79ebf1cb4b06b56b09f09de (diff)
iommu: arm-smmu-impl: Add sdm845 implementation hook
Add reset hook for sdm845 based platforms to turn off the wait-for-safe sequence. Understanding how wait-for-safe logic affects USB and UFS performance on MTP845 and DB845 boards: Qcom's implementation of arm,mmu-500 adds a WAIT-FOR-SAFE logic to address under-performance issues in real-time clients, such as Display, and Camera. On receiving an invalidation requests, the SMMU forwards SAFE request to these clients and waits for SAFE ack signal from real-time clients. The SAFE signal from such clients is used to qualify the start of invalidation. This logic is controlled by chicken bits, one for each - MDP (display), IFE0, and IFE1 (camera), that can be accessed only from secure software on sdm845. This configuration, however, degrades the performance of non-real time clients, such as USB, and UFS etc. This happens because, with wait-for-safe logic enabled the hardware tries to throttle non-real time clients while waiting for SAFE ack signals from real-time clients. On mtp845 and db845 devices, with wait-for-safe logic enabled by the bootloaders we see degraded performance of USB and UFS when kernel enables the smmu stage-1 translations for these clients. Turn off this wait-for-safe logic from the kernel gets us back the perf of USB and UFS devices until we re-visit this when we start seeing perf issues on display/camera on upstream supported SDM845 platforms. The bootloaders on these boards implement secure monitor callbacks to handle a specific command - QCOM_SCM_SVC_SMMU_PROGRAM with which the logic can be toggled. There are other boards such as cheza whose bootloaders don't enable this logic. Such boards don't implement callbacks to handle the specific SCM call so disabling this logic for such boards will be a no-op. This change is inspired by the downstream change from Patrick Daly to address performance issues with display and camera by handling this wait-for-safe within separte io-pagetable ops to do TLB maintenance. So a big thanks to him for the change and for all the offline discussions. Without this change the UFS reads are pretty slow: $ time dd if=/dev/sda of=/dev/zero bs=1048576 count=10 conv=sync 10+0 records in 10+0 records out 10485760 bytes (10.0MB) copied, 22.394903 seconds, 457.2KB/s real 0m 22.39s user 0m 0.00s sys 0m 0.01s With this change they are back to rock! $ time dd if=/dev/sda of=/dev/zero bs=1048576 count=300 conv=sync 300+0 records in 300+0 records out 314572800 bytes (300.0MB) copied, 1.030541 seconds, 291.1MB/s real 0m 1.03s user 0m 0.00s sys 0m 0.54s Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/Makefile2
-rw-r--r--drivers/iommu/arm-smmu-impl.c5
-rw-r--r--drivers/iommu/arm-smmu-qcom.c51
-rw-r--r--drivers/iommu/arm-smmu.h3
4 files changed, 59 insertions, 2 deletions
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 4f405f926e73..86dadd13b2e6 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -13,7 +13,7 @@ obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o amd_iommu_quirks.o
obj-$(CONFIG_AMD_IOMMU_DEBUGFS) += amd_iommu_debugfs.o
obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
-obj-$(CONFIG_ARM_SMMU) += arm-smmu.o arm-smmu-impl.o
+obj-$(CONFIG_ARM_SMMU) += arm-smmu.o arm-smmu-impl.o arm-smmu-qcom.o
obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
obj-$(CONFIG_DMAR_TABLE) += dmar.o
obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o intel-pasid.o
diff --git a/drivers/iommu/arm-smmu-impl.c b/drivers/iommu/arm-smmu-impl.c
index 5c87a38620c4..b2fe72a8f019 100644
--- a/drivers/iommu/arm-smmu-impl.c
+++ b/drivers/iommu/arm-smmu-impl.c
@@ -109,7 +109,7 @@ static struct arm_smmu_device *cavium_smmu_impl_init(struct arm_smmu_device *smm
#define ARM_MMU500_ACR_S2CRB_TLBEN (1 << 10)
#define ARM_MMU500_ACR_SMTNMB_TLBEN (1 << 8)
-static int arm_mmu500_reset(struct arm_smmu_device *smmu)
+int arm_mmu500_reset(struct arm_smmu_device *smmu)
{
u32 reg, major;
int i;
@@ -170,5 +170,8 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
"calxeda,smmu-secure-config-access"))
smmu->impl = &calxeda_impl;
+ if (of_device_is_compatible(smmu->dev->of_node, "qcom,sdm845-smmu-500"))
+ return qcom_smmu_impl_init(smmu);
+
return smmu;
}
diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c
new file mode 100644
index 000000000000..24c071c1d8b0
--- /dev/null
+++ b/drivers/iommu/arm-smmu-qcom.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/qcom_scm.h>
+
+#include "arm-smmu.h"
+
+struct qcom_smmu {
+ struct arm_smmu_device smmu;
+};
+
+static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
+{
+ int ret;
+
+ arm_mmu500_reset(smmu);
+
+ /*
+ * To address performance degradation in non-real time clients,
+ * such as USB and UFS, turn off wait-for-safe on sdm845 based boards,
+ * such as MTP and db845, whose firmwares implement secure monitor
+ * call handlers to turn on/off the wait-for-safe logic.
+ */
+ ret = qcom_scm_qsmmu500_wait_safe_toggle(0);
+ if (ret)
+ dev_warn(smmu->dev, "Failed to turn off SAFE logic\n");
+
+ return ret;
+}
+
+static const struct arm_smmu_impl qcom_smmu_impl = {
+ .reset = qcom_sdm845_smmu500_reset,
+};
+
+struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu)
+{
+ struct qcom_smmu *qsmmu;
+
+ qsmmu = devm_kzalloc(smmu->dev, sizeof(*qsmmu), GFP_KERNEL);
+ if (!qsmmu)
+ return ERR_PTR(-ENOMEM);
+
+ qsmmu->smmu = *smmu;
+
+ qsmmu->smmu.impl = &qcom_smmu_impl;
+ devm_kfree(smmu->dev, smmu);
+
+ return &qsmmu->smmu;
+}
diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
index 409716410b0d..62b9f0cec49b 100644
--- a/drivers/iommu/arm-smmu.h
+++ b/drivers/iommu/arm-smmu.h
@@ -395,5 +395,8 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
arm_smmu_writeq((s), ARM_SMMU_CB((s), (n)), (o), (v))
struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu);
+struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu);
+
+int arm_mmu500_reset(struct arm_smmu_device *smmu);
#endif /* _ARM_SMMU_H */