iommu/arm-smmu-qcom: Initialize SCTLR of the bypass context

On SM8150 it's occasionally observed that the boot hangs in between the
writing of SMEs and context banks in arm_smmu_device_reset().

The problem seems to coincide with a display refresh happening after
updating the stream mapping, but before clearing - and there by
disabling translation - the context bank picked to emulate translation
bypass.

Resolve this by explicitly disabling the bypass context already in
cfg_probe.

Fixes: f9081b8ff5 ("iommu/arm-smmu-qcom: Implement S2CR quirk")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210106005038.4152731-1-bjorn.andersson@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c

@@ -196,6 +196,8 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
 
 		set_bit(qsmmu->bypass_cbndx, smmu->context_map);
 
+		arm_smmu_cb_write(smmu, qsmmu->bypass_cbndx, ARM_SMMU_CB_SCTLR, 0);
+
 		reg = FIELD_PREP(ARM_SMMU_CBAR_TYPE, CBAR_TYPE_S1_TRANS_S2_BYPASS);
 		arm_smmu_gr1_write(smmu, ARM_SMMU_GR1_CBAR(qsmmu->bypass_cbndx), reg);
 	}