nv40: use native Z24_S8 format for zeta buffer

src/mesa/pipe/nv40/nv40_clear.c

@@ -10,12 +10,6 @@ void
 nv40_clear(struct pipe_context *pipe, struct pipe_surface *ps,
 	   unsigned clearValue)
 {
-	/*XXX: We're actually Z24_S8... */
-	if (ps->format == PIPE_FORMAT_S8_Z24) {
-		clearValue = (((clearValue & 0xff000000) >> 24) |
-			      ((clearValue & 0x00ffffff) <<  8));
-	}
-
 	pipe->region_fill(pipe, ps->region, 0, 0, 0, ps->width, ps->height,
 			  clearValue);
 }

src/mesa/pipe/nv40/nv40_context.c

@@ -12,7 +12,7 @@ nv40_is_format_supported(struct pipe_context *pipe, uint format)
 	switch (format) {
 	case PIPE_FORMAT_U_A8_R8_G8_B8:
 	case PIPE_FORMAT_U_R5_G6_B5: 
-	case PIPE_FORMAT_S8_Z24: 
+	case PIPE_FORMAT_Z24_S8:
 		return TRUE;
 	default:
 		break;

src/mesa/pipe/nv40/nv40_surface.c

@@ -79,7 +79,7 @@ nv40_get_tile_rgba(struct pipe_context *pipe,
          p += w0 * 4;
       }
       break;
-   case PIPE_FORMAT_S8_Z24:
+   case PIPE_FORMAT_Z24_S8:
       {
          const float scale = 1.0 / (float) 0xffffff;
          for (i = 0; i < h; i++) {
@@ -89,7 +89,7 @@ nv40_get_tile_rgba(struct pipe_context *pipe,
                pRow[0] =
                pRow[1] =
                pRow[2] =
-               pRow[3] = (pixel & 0xffffff) * scale;
+               pRow[3] = ((pixel & 0xffffff) >> 8) * scale;
                pRow += 4;
             }
             src += ps->region->pitch;