diff --git a/arch/mips/ralink/mt7621.c b/arch/mips/ralink/mt7621.c
index bd71f5b14238..d6efffd4dd20 100644
--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -10,6 +10,8 @@
 #include <linux/slab.h>
 #include <linux/sys_soc.h>
 #include <linux/memblock.h>
+#include <linux/pci.h>
+#include <linux/bug.h>
 
 #include <asm/bootinfo.h>
 #include <asm/mipsregs.h>
@@ -22,6 +24,35 @@
 
 static void *detect_magic __initdata = detect_memory_region;
 
+int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
+{
+	struct resource_entry *entry;
+	resource_size_t mask;
+
+	entry = resource_list_first_type(&bridge->windows, IORESOURCE_MEM);
+	if (!entry) {
+		pr_err("Cannot get memory resource\n");
+		return -EINVAL;
+	}
+
+	if (mips_cps_numiocu(0)) {
+		/*
+		 * Hardware doesn't accept mask values with 1s after
+		 * 0s (e.g. 0xffef), so warn if that's happen
+		 */
+		mask = ~(entry->res->end - entry->res->start) & CM_GCR_REGn_MASK_ADDRMASK;
+		WARN_ON(mask && BIT(ffz(~mask)) - 1 != ~mask);
+
+		write_gcr_reg1_base(entry->res->start);
+		write_gcr_reg1_mask(mask | CM_GCR_REGn_MASK_CMTGT_IOCU0);
+		pr_info("PCI coherence region base: 0x%08llx, mask/settings: 0x%08llx\n",
+			(unsigned long long)read_gcr_reg1_base(),
+			(unsigned long long)read_gcr_reg1_mask());
+	}
+
+	return 0;
+}
+
 phys_addr_t mips_cpc_default_phys_base(void)
 {
 	panic("Cannot detect cpc address");
diff --git a/drivers/pci/controller/pcie-mt7621.c b/drivers/pci/controller/pcie-mt7621.c
index 4138c0e83513..42cce31df943 100644
--- a/drivers/pci/controller/pcie-mt7621.c
+++ b/drivers/pci/controller/pcie-mt7621.c
@@ -208,37 +208,6 @@ static inline void mt7621_control_deassert(struct mt7621_pcie_port *port)
 		reset_control_assert(port->pcie_rst);
 }
 
-static int setup_cm_memory_region(struct pci_host_bridge *host)
-{
-	struct mt7621_pcie *pcie = pci_host_bridge_priv(host);
-	struct device *dev = pcie->dev;
-	struct resource_entry *entry;
-	resource_size_t mask;
-
-	entry = resource_list_first_type(&host->windows, IORESOURCE_MEM);
-	if (!entry) {
-		dev_err(dev, "cannot get memory resource\n");
-		return -EINVAL;
-	}
-
-	if (mips_cps_numiocu(0)) {
-		/*
-		 * FIXME: hardware doesn't accept mask values with 1s after
-		 * 0s (e.g. 0xffef), so it would be great to warn if that's
-		 * about to happen
-		 */
-		mask = ~(entry->res->end - entry->res->start);
-
-		write_gcr_reg1_base(entry->res->start);
-		write_gcr_reg1_mask(mask | CM_GCR_REGn_MASK_CMTGT_IOCU0);
-		dev_info(dev, "PCI coherence region base: 0x%08llx, mask/settings: 0x%08llx\n",
-			 (unsigned long long)read_gcr_reg1_base(),
-			 (unsigned long long)read_gcr_reg1_mask());
-	}
-
-	return 0;
-}
-
 static int mt7621_pcie_parse_port(struct mt7621_pcie *pcie,
 				  struct device_node *node,
 				  int slot)
@@ -557,12 +526,6 @@ static int mt7621_pci_probe(struct platform_device *pdev)
 		goto remove_resets;
 	}
 
-	err = setup_cm_memory_region(bridge);
-	if (err) {
-		dev_err(dev, "error setting up iocu mem regions\n");
-		goto remove_resets;
-	}
-
 	return mt7621_pcie_register_host(bridge);
 
 remove_resets: