On qcom msm8998, writing to the last context bank of lpass_q6_smmu
(base address 0x05100000) produces a system freeze & reboot.
Specifically, here:
qsmmu->bypass_cbndx = smmu->num_context_banks - 1;
arm_smmu_cb_write(smmu, qsmmu->bypass_cbndx, ARM_SMMU_CB_SCTLR, 0);
and here:
arm_smmu_write_context_bank(smmu, i);
arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_FSR, ARM_SMMU_CB_FSR_FAULT);
It is likely that FW reserves the last context bank for its own use,
thus a simple work-around would be: DON'T USE IT in Linux.
If we decrease the number of context banks, last one will be "hidden".
Signed-off-by: Marc Gonzalez <mgonzalez@xxxxxxxxxx>
---
drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 7e65189ca7b8c..e2e1fd9e2452b 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -282,6 +282,11 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
u32 smr;
int i;
+ if (of_property_read_bool(smmu->dev->of_node, "qcom,last-ctx-bank-reserved")) {
+ dev_warn(smmu->dev, "hiding last ctx bank from linux");
+ --smmu->num_context_banks;
+ }
+
/*
* Some platforms support more than the Arm SMMU architected maximum of
* 128 stream matching groups. For unknown reasons, the additional
--
2.34.1
