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)" <jirislaby@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-parisc@vger.kernel.org
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-31-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/vt.c

@@ -970,7 +970,7 @@ void redraw_screen(struct vc_data *vc, int is_switch)
 	}
 
 	if (redraw) {
-		int update;
+		bool update;
 		int old_was_color = vc->vc_can_do_color;
 
 		set_origin(vc);

drivers/video/console/dummycon.c

@@ -122,9 +122,9 @@ static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
 	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

@@ -446,9 +446,9 @@ static void mdacon_clear(struct vc_data *c, unsigned int y, unsigned int x,
 	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

@@ -459,7 +459,7 @@ static void newport_cursor(struct vc_data *vc, bool enable)
 	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;
 
@@ -473,7 +473,7 @@ static int newport_switch(struct vc_data *vc)
 		}
 	}
 
-	return 1;
+	return true;
 }
 
 static int newport_blank(struct vc_data *c, int blank, int mode_switch)

drivers/video/console/sticon.c

@@ -293,9 +293,9 @@ static void sticon_clear(struct vc_data *conp, unsigned int sy, unsigned int sx,
 	      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

@@ -614,7 +614,7 @@ static void vgacon_doresize(struct vc_data *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;
@@ -643,7 +643,7 @@ static int vgacon_switch(struct vc_data *c)
 			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

@@ -2056,7 +2056,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
 	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;
@@ -2178,9 +2178,9 @@ static int fbcon_switch(struct vc_data *vc)
 			      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

@@ -46,6 +46,8 @@ enum vc_intensity;
  * @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)
@@ -66,7 +68,7 @@ struct consw {
 	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);