iommu/arm-smmu-qcom: record reason for deferring probe

To avoid deferring probe smmu driver silently, record reason for it.
It can be checked through ../debugfs/devices_deferred as well:
/sys/kernel/debug# cat devices_deferred
15000000.iommu  arm-smmu: qcom_scm not ready

Signed-off-by: Zhenhua Huang <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Zhenhua Huang

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

@@ -469,7 +469,8 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
 
 	/* Check to make sure qcom_scm has finished probing */
 	if (!qcom_scm_is_available())
-		return ERR_PTR(-EPROBE_DEFER);
+		return ERR_PTR(dev_err_probe(smmu->dev, -EPROBE_DEFER,
+			"qcom_scm not ready\n"));
 
 	qsmmu = devm_krealloc(smmu->dev, smmu, sizeof(*qsmmu), GFP_KERNEL);
 	if (!qsmmu)