diff --git a/arch/mips/include/asm/mach-ralink/mt7621.h b/arch/mips/include/asm/mach-ralink/mt7621.h
index e1af1ba50bd8ce9b086dc13856f508ba80d22d04..6bbf082dd149ef90571ae8137d66eb9d4f14af05 100644
--- a/arch/mips/include/asm/mach-ralink/mt7621.h
+++ b/arch/mips/include/asm/mach-ralink/mt7621.h
@@ -24,9 +24,10 @@
 #define CHIP_REV_VER_SHIFT		8
 #define CHIP_REV_ECO_MASK		0xf
 
-#define MT7621_DRAM_BASE                0x0
-#define MT7621_DDR2_SIZE_MIN		32
-#define MT7621_DDR2_SIZE_MAX		256
+#define MT7621_LOWMEM_BASE		0x0
+#define MT7621_LOWMEM_MAX_SIZE		0x1C000000
+#define MT7621_HIGHMEM_BASE		0x20000000
+#define MT7621_HIGHMEM_SIZE		0x4000000
 
 #define MT7621_CHIP_NAME0		0x3637544D
 #define MT7621_CHIP_NAME1		0x20203132
diff --git a/arch/mips/ralink/common.h b/arch/mips/ralink/common.h
index 49ae370d023d70d1cf11e265810c2e9e6337a9d3..87fc16751281ed0363d050d145e5441d83626aad 100644
--- a/arch/mips/ralink/common.h
+++ b/arch/mips/ralink/common.h
@@ -17,6 +17,7 @@ struct ralink_soc_info {
 	unsigned long mem_size;
 	unsigned long mem_size_min;
 	unsigned long mem_size_max;
+	void (*mem_detect)(void);
 };
 extern struct ralink_soc_info soc_info;
 
diff --git a/arch/mips/ralink/mt7621.c b/arch/mips/ralink/mt7621.c
index ec87ce5610493c46d0fed425f1f0b55fd4426f76..6b3db98894cbc1cbc6e06175cac1d6483bdafbb0 100644
--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -9,7 +9,9 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/sys_soc.h>
+#include <linux/memblock.h>
 
+#include <asm/bootinfo.h>
 #include <asm/mipsregs.h>
 #include <asm/smp-ops.h>
 #include <asm/mips-cps.h>
@@ -49,6 +51,8 @@
 #define MT7621_GPIO_MODE_SDHCI_SHIFT	18
 #define MT7621_GPIO_MODE_SDHCI_GPIO	1
 
+static void *detect_magic __initdata = detect_memory_region;
+
 static struct rt2880_pmx_func uart1_grp[] =  { FUNC("uart1", 0, 1, 2) };
 static struct rt2880_pmx_func i2c_grp[] =  { FUNC("i2c", 0, 3, 2) };
 static struct rt2880_pmx_func uart3_grp[] = {
@@ -110,6 +114,26 @@ phys_addr_t mips_cpc_default_phys_base(void)
 	panic("Cannot detect cpc address");
 }
 
+static void __init mt7621_memory_detect(void)
+{
+	void *dm = &detect_magic;
+	phys_addr_t size;
+
+	for (size = 32 * SZ_1M; size < 256 * SZ_1M; size <<= 1) {
+		if (!__builtin_memcmp(dm, dm + size, sizeof(detect_magic)))
+			break;
+	}
+
+	if ((size == 256 * SZ_1M) &&
+	    (CPHYSADDR(dm + size) < MT7621_LOWMEM_MAX_SIZE) &&
+	    __builtin_memcmp(dm, dm + size, sizeof(detect_magic))) {
+		memblock_add(MT7621_LOWMEM_BASE, MT7621_LOWMEM_MAX_SIZE);
+		memblock_add(MT7621_HIGHMEM_BASE, MT7621_HIGHMEM_SIZE);
+	} else {
+		memblock_add(MT7621_LOWMEM_BASE, size);
+	}
+}
+
 void __init ralink_of_remap(void)
 {
 	rt_sysc_membase = plat_of_remap_node("mtk,mt7621-sysc");
@@ -194,10 +218,7 @@ void __init prom_soc_init(struct ralink_soc_info *soc_info)
 		(rev >> CHIP_REV_VER_SHIFT) & CHIP_REV_VER_MASK,
 		(rev & CHIP_REV_ECO_MASK));
 
-	soc_info->mem_size_min = MT7621_DDR2_SIZE_MIN;
-	soc_info->mem_size_max = MT7621_DDR2_SIZE_MAX;
-	soc_info->mem_base = MT7621_DRAM_BASE;
-
+	soc_info->mem_detect = mt7621_memory_detect;
 	rt2880_pinmux_data = mt7621_pinmux_data;
 
 	soc_dev_init(soc_info, rev);
diff --git a/arch/mips/ralink/of.c b/arch/mips/ralink/of.c
index 8286c3521476f2840ab425ab0b1796bc7bbb8698..0c5de07da097ad5e9733aaffa100debb6699d0d3 100644
--- a/arch/mips/ralink/of.c
+++ b/arch/mips/ralink/of.c
@@ -78,6 +78,8 @@ void __init plat_mem_setup(void)
 	of_scan_flat_dt(early_init_dt_find_memory, NULL);
 	if (memory_dtb)
 		of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+	else if (soc_info.mem_detect)
+		soc_info.mem_detect();
 	else if (soc_info.mem_size)
 		memblock_add(soc_info.mem_base, soc_info.mem_size * SZ_1M);
 	else