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 <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index b61ab3b4c922..ea67dd902d4e 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