diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 5e046587eef4..1072a10e36ce 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -240,6 +240,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 {
 	struct list_head *head = data->hw_list;
 	bool has_pm = !!data->dev->pm_domain;
+	void __iomem *base = data->base;
 	unsigned long flags;
 	int ret;
 	u32 tmp;
@@ -252,17 +253,15 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 
 		spin_lock_irqsave(&data->tlb_lock, flags);
 		writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
-			       data->base + data->plat_data->inv_sel_reg);
+			       base + data->plat_data->inv_sel_reg);
 
-		writel_relaxed(MTK_IOMMU_TLB_ADDR(iova),
-			       data->base + REG_MMU_INVLD_START_A);
+		writel_relaxed(MTK_IOMMU_TLB_ADDR(iova), base + REG_MMU_INVLD_START_A);
 		writel_relaxed(MTK_IOMMU_TLB_ADDR(iova + size - 1),
-			       data->base + REG_MMU_INVLD_END_A);
-		writel_relaxed(F_MMU_INV_RANGE,
-			       data->base + REG_MMU_INVALIDATE);
+			       base + REG_MMU_INVLD_END_A);
+		writel_relaxed(F_MMU_INV_RANGE, base + REG_MMU_INVALIDATE);
 
 		/* tlb sync */
-		ret = readl_poll_timeout_atomic(data->base + REG_MMU_CPE_DONE,
+		ret = readl_poll_timeout_atomic(base + REG_MMU_CPE_DONE,
 						tmp, tmp != 0, 10, 1000);
 		if (ret) {
 			dev_warn(data->dev,
@@ -270,7 +269,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 			mtk_iommu_tlb_flush_all(data);
 		}
 		/* Clear the CPE status */
-		writel_relaxed(0, data->base + REG_MMU_CPE_DONE);
+		writel_relaxed(0, base + REG_MMU_CPE_DONE);
 		spin_unlock_irqrestore(&data->tlb_lock, flags);
 
 		if (has_pm)
@@ -284,23 +283,25 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
 	struct mtk_iommu_domain *dom = data->m4u_dom;
 	unsigned int fault_larb = 0, fault_port = 0, sub_comm = 0;
 	u32 int_state, regval, va34_32, pa34_32;
+	const struct mtk_iommu_plat_data *plat_data = data->plat_data;
+	void __iomem *base = data->base;
 	u64 fault_iova, fault_pa;
 	bool layer, write;
 
 	/* Read error info from registers */
-	int_state = readl_relaxed(data->base + REG_MMU_FAULT_ST1);
+	int_state = readl_relaxed(base + REG_MMU_FAULT_ST1);
 	if (int_state & F_REG_MMU0_FAULT_MASK) {
-		regval = readl_relaxed(data->base + REG_MMU0_INT_ID);
-		fault_iova = readl_relaxed(data->base + REG_MMU0_FAULT_VA);
-		fault_pa = readl_relaxed(data->base + REG_MMU0_INVLD_PA);
+		regval = readl_relaxed(base + REG_MMU0_INT_ID);
+		fault_iova = readl_relaxed(base + REG_MMU0_FAULT_VA);
+		fault_pa = readl_relaxed(base + REG_MMU0_INVLD_PA);
 	} else {
-		regval = readl_relaxed(data->base + REG_MMU1_INT_ID);
-		fault_iova = readl_relaxed(data->base + REG_MMU1_FAULT_VA);
-		fault_pa = readl_relaxed(data->base + REG_MMU1_INVLD_PA);
+		regval = readl_relaxed(base + REG_MMU1_INT_ID);
+		fault_iova = readl_relaxed(base + REG_MMU1_FAULT_VA);
+		fault_pa = readl_relaxed(base + REG_MMU1_INVLD_PA);
 	}
 	layer = fault_iova & F_MMU_FAULT_VA_LAYER_BIT;
 	write = fault_iova & F_MMU_FAULT_VA_WRITE_BIT;
-	if (MTK_IOMMU_HAS_FLAG(data->plat_data, IOVA_34_EN)) {
+	if (MTK_IOMMU_HAS_FLAG(plat_data, IOVA_34_EN)) {
 		va34_32 = FIELD_GET(F_MMU_INVAL_VA_34_32_MASK, fault_iova);
 		fault_iova = fault_iova & F_MMU_INVAL_VA_31_12_MASK;
 		fault_iova |= (u64)va34_32 << 32;
@@ -308,12 +309,12 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
 	pa34_32 = FIELD_GET(F_MMU_INVAL_PA_34_32_MASK, fault_iova);
 	fault_pa |= (u64)pa34_32 << 32;
 
-	if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM)) {
+	if (MTK_IOMMU_IS_TYPE(plat_data, MTK_IOMMU_TYPE_MM)) {
 		fault_port = F_MMU_INT_ID_PORT_ID(regval);
-		if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_SUB_COMM_2BITS)) {
+		if (MTK_IOMMU_HAS_FLAG(plat_data, HAS_SUB_COMM_2BITS)) {
 			fault_larb = F_MMU_INT_ID_COMM_ID(regval);
 			sub_comm = F_MMU_INT_ID_SUB_COMM_ID(regval);
-		} else if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_SUB_COMM_3BITS)) {
+		} else if (MTK_IOMMU_HAS_FLAG(plat_data, HAS_SUB_COMM_3BITS)) {
 			fault_larb = F_MMU_INT_ID_COMM_ID_EXT(regval);
 			sub_comm = F_MMU_INT_ID_SUB_COMM_ID_EXT(regval);
 		} else {
@@ -332,9 +333,9 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
 	}
 
 	/* Interrupt clear */
-	regval = readl_relaxed(data->base + REG_MMU_INT_CONTROL0);
+	regval = readl_relaxed(base + REG_MMU_INT_CONTROL0);
 	regval |= F_INT_CLR_BIT;
-	writel_relaxed(regval, data->base + REG_MMU_INT_CONTROL0);
+	writel_relaxed(regval, base + REG_MMU_INT_CONTROL0);
 
 	mtk_iommu_tlb_flush_all(data);
 
