[PATCH] neofb: take existing display configuration as default

On a Dell Latitude CPi-A I noticed a strangeness wrt.  the handling of an
external monitor by the neomagic framebuffer driver, namely when the laptop is
docked in a C/Dock II with the lid shut.

A cold boot would result in the BIOS configuring the video chip to use the
"external monitor only" mode, yet neofb would default to "internal LCD only".
An attempt for a quick fix by using the Fn-F8 keystroke to toggle the display
combination modes resulted in a reproductible hard lock, powering down being
the only solution.

The attached patch makes neofb probe the register for the current display
mode, using that value as a default if nothing was specified as kernel/module
parameter.

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

diff --git a/drivers/video/neofb.c b/drivers/video/neofb.c
index e18c9f9..747602a 100644 (file)
--- a/drivers/video/neofb.c
+++ b/drivers/video/neofb.c
@@ -853,7 +853,7 @@ static int neofb_set_par(struct fb_info *info)
        /* If the user did not specify any display devices, then... */
        if (par->PanelDispCntlReg1 == 0x00) {
                /* Default to internal (i.e., LCD) only. */
-               par->PanelDispCntlReg1 |= 0x02;
+               par->PanelDispCntlReg1 = vga_rgfx(NULL, 0x20) & 0x03;
        }
 
        /* If we are using a fixed mode, then tell the chip we are. */