tty: vt: make consw::con_switch() return a bool

The non-zero (true) return value from consw::con_switch() means a redraw
is needed. So make this return type a bool explicitly instead of int.
The latter might imply that -Eerrors are expected. They are not.

And document the hook.

Signed-off-by: "Jiri Slaby (SUSE)" <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: "James E.J. Bottomley" <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Tested-by: Helge Deller <[e-mail]> # parisc STI console
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/vt/vt.c

···
 	}
 
 	if (redraw) {
-		int update;
+		bool update;
 		int old_was_color = vc->vc_can_do_color;
 
 		set_origin(vc);

drivers/video/console/dummycon.c

···
 	return false;
 }
 
-static int dummycon_switch(struct vc_data *vc)
+static bool dummycon_switch(struct vc_data *vc)
 {
-	return 0;
+	return false;
 }
 
 /*

drivers/video/console/mdacon.c

···
 	scr_memsetw(dest, eattr, width * 2);
 }
 
-static int mdacon_switch(struct vc_data *c)
+static bool mdacon_switch(struct vc_data *c)
 {
-	return 1;	/* redrawing needed */
+	return true;	/* redrawing needed */
 }
 
 static int mdacon_blank(struct vc_data *c, int blank, int mode_switch)

drivers/video/console/newport_con.c

···
 	newport_vc2_set(npregs, VC2_IREG_CURSY, ycurs);
 }
 
-static int newport_switch(struct vc_data *vc)
+static bool newport_switch(struct vc_data *vc)
 {
 	static int logo_drawn = 0;
 
···
 		}
 	}
 
-	return 1;
+	return true;
 }
 
 static int newport_blank(struct vc_data *c, int blank, int mode_switch)

drivers/video/console/sticon.c

···
 	      conp->vc_video_erase_char, font_data[conp->vc_num]);
 }
 
-static int sticon_switch(struct vc_data *conp)
+static bool sticon_switch(struct vc_data *conp)
 {
-    return 1;	/* needs refreshing */
+    return true;	/* needs refreshing */
 }
 
 static int sticon_blank(struct vc_data *c, int blank, int mode_switch)

drivers/video/console/vgacon.c

···
 	raw_spin_unlock_irqrestore(&vga_lock, flags);
 }
 
-static int vgacon_switch(struct vc_data *c)
+static bool vgacon_switch(struct vc_data *c)
 {
 	int x = c->vc_cols * VGA_FONTWIDTH;
 	int y = c->vc_rows * c->vc_cell_height;
···
 			vgacon_doresize(c, c->vc_cols, c->vc_rows);
 	}
 
-	return 0;		/* Redrawing not needed */
+	return false;		/* Redrawing not needed */
 }
 
 static void vga_set_palette(struct vc_data *vc, const unsigned char *table)

drivers/video/fbdev/core/fbcon.c

···
 	return 0;
 }
 
-static int fbcon_switch(struct vc_data *vc)
+static bool fbcon_switch(struct vc_data *vc)
 {
 	struct fb_info *info, *old_info = NULL;
 	struct fbcon_ops *ops;
···
 			      vc->vc_origin + vc->vc_size_row * vc->vc_top,
 			      vc->vc_size_row * (vc->vc_bottom -
 						 vc->vc_top) / 2);
-		return 0;
+		return false;
 	}
-	return 1;
+	return true;
 }
 
 static void fbcon_generic_blank(struct vc_data *vc, struct fb_info *info,

include/linux/console.h

···
  * @con_scroll: move lines from @top to @bottom in direction @dir by @lines.
  *		Return true if no generic handling should be done.
  *		Invoked by csi_M and printing to the console.
+ * @con_switch: notifier about the console switch; it is supposed to return
+ *		true if a redraw is needed.
  * @con_set_palette: sets the palette of the console to @table (optional)
  * @con_scrolldelta: the contents of the console should be scrolled by @lines.
  *		     Invoked by user. (optional)
···
 	bool	(*con_scroll)(struct vc_data *vc, unsigned int top,
 			unsigned int bottom, enum con_scroll dir,
 			unsigned int lines);
-	int	(*con_switch)(struct vc_data *vc);
+	bool	(*con_switch)(struct vc_data *vc);
 	int	(*con_blank)(struct vc_data *vc, int blank, int mode_switch);
 	int	(*con_font_set)(struct vc_data *vc, struct console_font *font,
 			unsigned int vpitch, unsigned int flags);