[PATCH] s3fb: fix Virge/VX

[Ondrej Zary <linux@rainbow-software.org>]

Add memory size detection for Virge/VX and small delay in mode setting (same
as in X.org driver) to fix blank screen problem.

Also adjust DTPC position to fix garbled screen in some modes (tested that
this adjustment does not break other cards - at least Trio32, Trio64V+,
Trio64V2/DX, Virge, Virge/DX).

Tested on ELSA Winner 2000AVI/3D.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>

--- linux-3.1-orig/drivers/video/s3fb.c	2011-10-24 09:10:05.000000000 +0200
+++ linux-3.1/drivers/video/s3fb.c	2011-12-19 23:28:34.000000000 +0100
@@ -727,7 +727,7 @@
 	if (par->chip = CHIP_988_VIRGE_VX) {
 		vga_wcrt(par->state.vgabase, 0x50, 0x00);
 		vga_wcrt(par->state.vgabase, 0x67, 0x50);
-
+		msleep(10); /* screen remains blank sometimes without this */
 		vga_wcrt(par->state.vgabase, 0x63, (mode <= 2) ? 0x90 : 0x09);
 		vga_wcrt(par->state.vgabase, 0x66, 0x90);
 	}
@@ -901,7 +901,8 @@
 
 	/* Set Data Transfer Position */
 	hsstart = ((info->var.xres + info->var.right_margin) * hmul) / 8;
-	value = clamp((htotal + hsstart + 1) / 2, hsstart + 4, htotal + 1);
+	/* + 2 is needed for Virge/VX, does no harm on other cards */
+	value = clamp((htotal + hsstart + 1) / 2 + 2, hsstart + 4, htotal + 1);
 	svga_wcrt_multi(par->state.vgabase, s3_dtpc_regs, value);
 
 	memset_io(info->screen_base, 0x00, screen_size);
@@ -1215,6 +1216,31 @@
 			info->screen_size = 2 << 20;
 			break;
 		}
+	} else if (par->chip = CHIP_988_VIRGE_VX) {
+		switch ((regval & 0x60) >> 5) {
+		case 0: /* 2MB */
+			info->screen_size = 2 << 20;
+			break;
+		case 1: /* 4MB */
+			info->screen_size = 4 << 20;
+			break;
+		case 2: /* 6MB */
+			info->screen_size = 6 << 20;
+			break;
+		case 3: /* 8MB */
+			info->screen_size = 8 << 20;
+			break;
+		}
+		/* off-screen memory */
+		regval = vga_rcrt(par->state.vgabase, 0x37);
+		switch ((regval & 0x60) >> 5) {
+		case 1: /* 4MB */
+			info->screen_size -= 4 << 20;
+			break;
+		case 2: /* 2MB */
+			info->screen_size -= 2 << 20;
+			break;
+		}
 	} else
 		info->screen_size = s3_memsizes[regval >> 5] << 10;
 	info->fix.smem_len = info->screen_size;


-- 
Ondrej Zary