Messages in this thread | | | Date | Sun, 26 Jul 2020 23:27:03 -0700 | From | Bjorn Andersson <> | Subject | Re: [PATCH v10 04/13] iommu/arm-smmu-qcom: Add implementation for the adreno GPU SMMU |
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On Mon 20 Jul 08:40 PDT 2020, Jordan Crouse wrote: > diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c [..] > +static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_domain, > + struct device *dev, int start, int count) > +{ > + struct arm_smmu_device *smmu = smmu_domain->smmu; > + > + /* > + * Assign context bank 0 to the GPU device so the GPU hardware can > + * switch pagetables > + */ > + if (qcom_adreno_smmu_is_gpu_device(dev)) { > + if (start > 0 || test_bit(0, smmu->context_map)) > + return -ENOSPC; > + > + set_bit(0, smmu->context_map); > + return 0; > + } > + > + return __arm_smmu_alloc_bitmap(smmu->context_map, start, count);
If we end up here before the GPU device shows up this is going to steal the first context bank, causing the subsequent allocation for the GPU to always fail.
As such I think it would be appropriate for you to adjust "start" to never be 0 here. And I think it would be appropriate to write this function as:
if (gpu) { start = 0; count = 1; } else { if (start == 0) start = 1; }
return __arm_smmu_alloc_bitmap(smmu->context_map, start, count);
Regards, Bjorn
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