nvidiafb: Add proper support for Geforce 7600 chipset

Add proper support for the Geforce 7600 (device id 0x039x).  This also sync's
nvidiafb with the latest Xorg nv driver.

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>
diff --git a/drivers/video/nvidia/nv_setup.c b/drivers/video/nvidia/nv_setup.c
index 707e2c8..82579d3 100644
--- a/drivers/video/nvidia/nv_setup.c
+++ b/drivers/video/nvidia/nv_setup.c
@@ -166,11 +166,13 @@
 static int NVIsConnected(struct nvidia_par *par, int output)
 {
 	volatile u32 __iomem *PRAMDAC = par->PRAMDAC0;
-	u32 reg52C, reg608;
+	u32 reg52C, reg608, dac0_reg608 = 0;
 	int present;
 
-	if (output)
-		PRAMDAC += 0x800;
+	if (output) {
+	    dac0_reg608 = NV_RD32(PRAMDAC, 0x0608);
+	    PRAMDAC += 0x800;
+	}
 
 	reg52C = NV_RD32(PRAMDAC, 0x052C);
 	reg608 = NV_RD32(PRAMDAC, 0x0608);
@@ -194,8 +196,8 @@
 	else
 		printk("nvidiafb: CRTC%i analog not found\n", output);
 
-	NV_WR32(par->PRAMDAC0, 0x0608, NV_RD32(par->PRAMDAC0, 0x0608) &
-		0x0000EFFF);
+	if (output)
+	    NV_WR32(par->PRAMDAC0, 0x0608, dac0_reg608);
 
 	NV_WR32(PRAMDAC, 0x052C, reg52C);
 	NV_WR32(PRAMDAC, 0x0608, reg608);