[PATCH] radeon: fix overlapping copyarea

This fixes a corruption problem with overlapping copyarea()'s
in the radeon driver.

drivers/video/aty/radeon_accel.c

@@ -53,6 +53,18 @@ void radeonfb_fillrect(struct fb_info *info, const struct fb_fillrect *region)
 static void radeonfb_prim_copyarea(struct radeonfb_info *rinfo, 
 				   const struct fb_copyarea *area)
 {
+	int xdir, ydir;
+	u32 sx, sy, dx, dy, w, h;
+
+	w = area->width; h = area->height;
+	dx = area->dx; dy = area->dy;
+	sx = area->sx; sy = area->sy;
+	xdir = sx - dx;
+	ydir = sy - dy;
+
+	if ( xdir < 0 ) { sx += w-1; dx += w-1; }
+	if ( ydir < 0 ) { sy += h-1; dy += h-1; }
+
 	radeon_fifo_wait(3);
 	OUTREG(DP_GUI_MASTER_CNTL,
 		rinfo->dp_gui_master_cntl /* i.e. GMC_DST_32BPP */
@@ -60,12 +72,13 @@ static void radeonfb_prim_copyarea(struct radeonfb_info *rinfo,
 		| ROP3_S 
 		| DP_SRC_RECT );
 	OUTREG(DP_WRITE_MSK, 0xffffffff);
-	OUTREG(DP_CNTL, (DST_X_LEFT_TO_RIGHT | DST_Y_TOP_TO_BOTTOM));
+	OUTREG(DP_CNTL, (xdir>=0 ? DST_X_LEFT_TO_RIGHT : 0)
+			| (ydir>=0 ? DST_Y_TOP_TO_BOTTOM : 0));
 
 	radeon_fifo_wait(3);
-	OUTREG(SRC_Y_X, (area->sy << 16) | area->sx);
-	OUTREG(DST_Y_X, (area->dy << 16) | area->dx);
-	OUTREG(DST_HEIGHT_WIDTH, (area->height << 16) | area->width);
+	OUTREG(SRC_Y_X, (sy << 16) | sx);
+	OUTREG(DST_Y_X, (dy << 16) | dx);
+	OUTREG(DST_HEIGHT_WIDTH, (h << 16) | w);
 }