[PATCH] tridentfb: Fix scrolling artifacts during disk IO

Reported by: Jochen Hein (Bugzilla Bug 4312)

When there is disk I/O happening, the framebuffer has a little snow on
the screen.  Once I/O has finished, no garbage remains on screen.

This bug was explained by: Knut Petersen

Most important is CRTC register 2f, signal quality is also improved for
higher vclk values by changing set_vclk() according to the X drivers and
cyblafb.c

The fix is to set the performance register (0x2f) with a more stable
value.
Signed-off-by: NAntonino Daplas <adaplas@pol.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/video/tridentfb.c

@@ -904,7 +904,7 @@ static int tridentfb_set_par(struct fb_info *info)
 	write3X4(DRAMControl, tmp);	//both IO,linear enable
 
 	write3X4(InterfaceSel, read3X4(InterfaceSel) | 0x40);
-	write3X4(Performance,0x20);
+	write3X4(Performance,0x92);
 	write3X4(PCIReg,0x07);		//MMIO & PCI read and write burst enable
 
 	/* convert from picoseconds to MHz */