[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: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/video/tridentfb.c b/drivers/video/tridentfb.c
index 64aa78c5da7993a18d7a1f0244f7c5fd2548ef45..698ca9232e73649c7669887685edca5e89b16698 100644 (file)
--- a/drivers/video/tridentfb.c
+++ b/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 */