Hi Jean,

On 2018/3/21 21:24, Jean-Philippe Brucker wrote:

Hi Yisheng,

On 19/03/18 11:03, Yisheng Xie wrote:

quoted

Hi Jean,

[...]

quoted

@@ -3168,6 +3260,13 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	if (smmu->features & (ARM_SMMU_FEAT_STALLS | ARM_SMMU_FEAT_PRI)) {
+		smmu->faultq_nb.notifier_call = arm_smmu_flush_queues;
+		ret = iommu_fault_queue_register(&smmu->faultq_nb);
+		if (ret)
+			return ret;

I find a case here: CONFIG_IOMMU_FAULT=n, and smmu support feature STALLS or PRI,
the device probe will failed here, is this what we want?

Since CONFIG_ARM_SMMU_V3 selects CONFIG_IOMMU_FAULT, I don't think it
can happen. 

But CONFIG_IOMMU_FAULT can be changed after select, maybe can make it as unchangeable.

Thanks
Yisheng

I'm not sure what the best practices are, but I feel like it
would be too much work to guard against config combinations that violate
an explicit "select" in Kconfig

Thanks,
Jean

.