diff --git a/drivers/iommu/riscv/iommu-platform.c b/drivers/iommu/riscv/iommu-platform.c
index 83a28c83f991..8f15b06e8499 100644
--- a/drivers/iommu/riscv/iommu-platform.c
+++ b/drivers/iommu/riscv/iommu-platform.c
@@ -68,12 +68,7 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 	iommu->caps = riscv_iommu_readq(iommu, RISCV_IOMMU_REG_CAPABILITIES);
 	iommu->fctl = riscv_iommu_readl(iommu, RISCV_IOMMU_REG_FCTL);
 
-	iommu->irqs_count = platform_irq_count(pdev);
-	if (iommu->irqs_count <= 0)
-		return dev_err_probe(dev, -ENODEV,
-				     "no IRQ resources provided\n");
-	if (iommu->irqs_count > RISCV_IOMMU_INTR_COUNT)
-		iommu->irqs_count = RISCV_IOMMU_INTR_COUNT;
+	iommu->irqs_count = RISCV_IOMMU_INTR_COUNT;
 
 	igs = FIELD_GET(RISCV_IOMMU_CAPABILITIES_IGS, iommu->caps);
 	switch (igs) {
@@ -120,6 +115,13 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 		fallthrough;
 
 	case RISCV_IOMMU_CAPABILITIES_IGS_WSI:
+		iommu->irqs_count = platform_irq_count(pdev);
+		if (iommu->irqs_count <= 0)
+			return dev_err_probe(dev, -ENODEV,
+					     "no IRQ resources provided\n");
+		if (iommu->irqs_count > RISCV_IOMMU_INTR_COUNT)
+			iommu->irqs_count = RISCV_IOMMU_INTR_COUNT;
+
 		for (vec = 0; vec < iommu->irqs_count; vec++)
 			iommu->irqs[vec] = platform_get_irq(pdev, vec);