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.
Signed-off-by: Marc Gonzalez <mgonzalez@xxxxxxxxxx>
---
Documentation/devicetree/bindings/iommu/arm,smmu.yaml | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
index 280b4e49f2191..f9b23aef351b0 100644
--- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
+++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
@@ -204,6 +204,12 @@ properties:
access to SMMU configuration registers. In this case non-secure aliases of
secure registers have to be used during SMMU configuration.
+ qcom,last-ctx-bank-reserved:
+ type: boolean
+ description:
+ FW reserves the last context bank of this SMMU for its own use.
+ If Linux tries to use it, Linux gets nuked.
+
stream-match-mask:
$ref: /schemas/types.yaml#/definitions/uint32
description: |
--
2.34.1
