neofb: take existing display configuration as default

From: Christian Trefzer <[email protected]>

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.

---

 drivers/video/neofb.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index e18c9f9..747602a 100644
@@ -853,7 +853,7 @@ static int neofb_set_par(struct fb_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. */

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