diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index b61ab3b4c922f9c7a4e036cf671d2015abc9b324..ea67dd902d4ea32654bd17efae35630a1ebdfcaa 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2377,6 +2377,9 @@ static int __devinit aty_init(struct fb_info *info)
 		/* for many chips, the mclk is 67 MHz for SDRAM, 63 MHz otherwise */
 		if (par->pll_limits.mclk == 67 && par->ram_type < SDRAM)
 			par->pll_limits.mclk = 63;
+		/* Mobility + 32bit memory interface need halved XCLK. */
+		if (M64_HAS(MOBIL_BUS) && par->ram_type == SDRAM32)
+			par->pll_limits.xclk = (par->pll_limits.xclk + 1) >> 1;
 	}
 #endif
 
diff --git a/include/video/mach64.h b/include/video/mach64.h
index 09a7f4a7289f429afffd976dc06c50d4dd605042..a8332e528ec19ef6d7b50540e615ec108ce36a0f 100644
--- a/include/video/mach64.h
+++ b/include/video/mach64.h
@@ -885,6 +885,7 @@
 #define SDRAM			4
 #define SGRAM			5
 #define WRAM			6
+#define SDRAM32			6
 
 #define DAC_INTERNAL		0x00
 #define DAC_IBMRGB514		0x01