atyfb: halve XCLK with Mobility and 32bit memory

Laptops with Rage Mobility and 32bit memory interface seem to require halved
XCLK to operate correctly.

Signed-off-by: Antonino Daplas <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/aty/atyfb_base.c

···
 		/* 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
 

include/video/mach64.h

···
 #define SDRAM			4
 #define SGRAM			5
 #define WRAM			6
+#define SDRAM32			6
 
 #define DAC_INTERNAL		0x00
 #define DAC_IBMRGB514		0x01