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Date: Tue, 24 May 2022 09:25:45 +0530
From: Sai Prakash Ranjan <quic_saipraka@...cinc.com>
To: Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
"Joerg Roedel" <joro@...tes.org>
CC: <iommu@...ts.linux-foundation.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Rob Clark <robdclark@...omium.org>, <quic_guptap@...cinc.com>
Subject: Re: [PATCH] iommu/arm-smmu-qcom: Add debug support for TLB sync
timeouts
On 5/23/2022 10:48 PM, Sai Prakash Ranjan wrote:
> TLB sync timeouts can be due to various reasons such as TBU power down
> or pending TCU/TBU invalidation/sync and so on. Debugging these often
> require dumping of some implementation defined registers to know the
> status of TBU/TCU operations and some of these registers are not
> accessible in non-secure world such as from kernel and requires SMC
> calls to read them in the secure world. So, add this debug support
> to dump implementation defined registers for TLB sync timeout issues.
>
> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@...cinc.com>
> ---
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 50 ++++++++++++++++++++++
> drivers/iommu/arm/arm-smmu/arm-smmu.c | 2 +
> drivers/iommu/arm/arm-smmu/arm-smmu.h | 4 ++
> 3 files changed, 56 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 7820711c4560..22e9a0085475 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -5,11 +5,19 @@
>
> #include <linux/acpi.h>
> #include <linux/adreno-smmu-priv.h>
> +#include <linux/delay.h>
> #include <linux/of_device.h>
> #include <linux/qcom_scm.h>
>
> #include "arm-smmu.h"
>
> +#define QCOM_DUMMY_VAL -1
> +
> +/* Implementation Defined Register Space 0 registers */
> +#define QCOM_SMMU_STATS_SYNC_INV_TBU_ACK 0x5dc
> +#define QCOM_SMMU_TBU_PWR_STATUS 0x2204
> +#define QCOM_SMMU_MMU2QSS_AND_SAFE_WAIT_CNTR 0x2670
> +
> struct qcom_smmu {
> struct arm_smmu_device smmu;
> bool bypass_quirk;
> @@ -22,6 +30,46 @@ static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
> return container_of(smmu, struct qcom_smmu, smmu);
> }
>
> +static void qcom_smmu_tlb_sync(struct arm_smmu_device *smmu, int page,
> + int sync, int status)
> +{
> + u32 sync_inv_ack, sync_inv_progress, tbu_pwr_status;
> + unsigned int spin_cnt, delay;
> + u32 reg;
> + int ret;
> +
> + arm_smmu_writel(smmu, page, sync, QCOM_DUMMY_VAL);
> + for (delay = 1; delay < TLB_LOOP_TIMEOUT; delay *= 2) {
> + for (spin_cnt = TLB_SPIN_COUNT; spin_cnt > 0; spin_cnt--) {
> + reg = arm_smmu_readl(smmu, page, status);
> + if (!(reg & ARM_SMMU_sTLBGSTATUS_GSACTIVE))
> + return;
> + cpu_relax();
> + }
> + udelay(delay);
> + }
> +
> + sync_inv_ack = arm_smmu_readl(smmu, ARM_SMMU_IMPL_DEF0,
> + QCOM_SMMU_STATS_SYNC_INV_TBU_ACK);
Sorry, this doesn't work always, looks like on earlier chipsets this is a secure register and
reading it from non-secure world would probably blow. Also this register can be in other
implementation defined space for different chipsets. So I think we can use SCM call here
and have a device specific data based on already existing compatible for QCOM SoCs to
identify IMP_DEF space used.
> + ret = qcom_scm_io_readl(smmu->ioaddr + QCOM_SMMU_TBU_PWR_STATUS,
> + &tbu_pwr_status);
> + if (ret)
> + dev_err_ratelimited(smmu->dev,
> + "Failed to read TBU power status: %d\n", ret);
> +
> + ret = qcom_scm_io_readl(smmu->ioaddr + QCOM_SMMU_MMU2QSS_AND_SAFE_WAIT_CNTR,
> + &sync_inv_progress);
> + if (ret)
> + dev_err_ratelimited(smmu->dev,
> + "Failed to read SAFE WAIT counter: %d\n", ret);
> +
> + dev_err_ratelimited(smmu->dev,
> + "TLB sync timed out -- SMMU may be deadlocked\n"
> + "TBU: sync_inv_ack %#x power_status %#x sync_inv_progress %#x\n",
> + sync_inv_ack, tbu_pwr_status, sync_inv_progress);
> +}
> +
> static void qcom_adreno_smmu_write_sctlr(struct arm_smmu_device *smmu, int idx,
> u32 reg)
> {
> @@ -374,6 +422,7 @@ static const struct arm_smmu_impl qcom_smmu_impl = {
> .def_domain_type = qcom_smmu_def_domain_type,
> .reset = qcom_smmu500_reset,
> .write_s2cr = qcom_smmu_write_s2cr,
> + .tlb_sync = qcom_smmu_tlb_sync,
> };
>
> static const struct arm_smmu_impl qcom_adreno_smmu_impl = {
> @@ -382,6 +431,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_impl = {
> .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,
> };
>
> static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index 2ed3594f384e..4c5b51109835 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -2099,6 +2099,8 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> if (IS_ERR(smmu->base))
> return PTR_ERR(smmu->base);
> ioaddr = res->start;
> + smmu->ioaddr = ioaddr;
> +
> /*
> * The resource size should effectively match the value of SMMU_TOP;
> * stash that temporarily until we know PAGESIZE to validate it with.
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index 2b9b42fb6f30..8cf6567d970f 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -278,6 +278,7 @@ struct arm_smmu_device {
> struct device *dev;
>
> void __iomem *base;
> + phys_addr_t ioaddr;
> unsigned int numpage;
> unsigned int pgshift;
>
> @@ -502,6 +503,9 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
>
> #define ARM_SMMU_GR0 0
> #define ARM_SMMU_GR1 1
> +
> +#define ARM_SMMU_IMPL_DEF0 2
> +
> #define ARM_SMMU_CB(s, n) ((s)->numpage + (n))
>
> #define arm_smmu_gr0_read(s, o) \
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