@@ -46,6 +46,8 @@
 #define F_MMU_STANDARD_AXI_MODE_BIT		(BIT(3) | BIT(19))
 
 #define REG_MMU_DCM_DIS				0x050
+#define REG_MMU_WR_LEN				0x054
+#define F_MMU_WR_THROT_DIS_BIT			(BIT(5) |  BIT(21))
 
 #define REG_MMU_CTRL_REG			0x110
 #define F_MMU_TF_PROT_TO_PROGRAM_ADDR		(2 << 4)

@@ -581,6 +583,12 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
 		writel_relaxed(regval, data->base + REG_MMU_VLD_PA_RNG);
 	}
 	writel_relaxed(0, data->base + REG_MMU_DCM_DIS);
+	if (data->plat_data->has_wr_len) {
+		/* write command throttling mode */
+		regval = readl_relaxed(data->base + REG_MMU_WR_LEN);
+		regval &= ~F_MMU_WR_THROT_DIS_BIT;
+		writel_relaxed(regval, data->base + REG_MMU_WR_LEN);
+	}
 
 	if (data->plat_data->reset_axi) {
 		/* The register is called STANDARD_AXI_MODE in this case */

@@ -737,6 +745,7 @@ static int __maybe_unused mtk_iommu_suspend(struct device *dev)
 	struct mtk_iommu_suspend_reg *reg = &data->reg;
 	void __iomem *base = data->base;
 
+	reg->wr_len = readl_relaxed(base + REG_MMU_WR_LEN);
 	reg->misc_ctrl = readl_relaxed(base + REG_MMU_MISC_CTRL);
 	reg->dcm_dis = readl_relaxed(base + REG_MMU_DCM_DIS);
 	reg->ctrl_reg = readl_relaxed(base + REG_MMU_CTRL_REG);

@@ -761,6 +770,7 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
 		dev_err(data->dev, "Failed to enable clk(%d) in resume\n", ret);
 		return ret;
 	}
+	writel_relaxed(reg->wr_len, base + REG_MMU_WR_LEN);
 	writel_relaxed(reg->misc_ctrl, base + REG_MMU_MISC_CTRL);
 	writel_relaxed(reg->dcm_dis, base + REG_MMU_DCM_DIS);
 	writel_relaxed(reg->ctrl_reg, base + REG_MMU_CTRL_REG);

@@ -25,6 +25,7 @@ struct mtk_iommu_suspend_reg {
 	u32				int_main_control;
 	u32				ivrp_paddr;
 	u32				vld_pa_rng;
+	u32				wr_len;
 };
 
 enum mtk_iommu_plat {

@@ -43,6 +44,7 @@ struct mtk_iommu_plat_data {
 	bool		    has_misc_ctrl;
 	bool		    has_sub_comm;
 	bool                has_vld_pa_rng;
+	bool                has_wr_len;
 	bool                reset_axi;
 	u32                 inv_sel_reg;
 	unsigned char       larbid_remap[8][4];