fbcon: call fbcon_fb_(un)registered directly

With

commit 6104c370
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Aug 1 17:32:07 2017 +0200

    fbcon: Make fbcon a built-time depency for fbdev

we have a static dependency between fbcon and fbdev, and we can
replace the indirection through the notifier chain with a function
call.

v2: Sam Ravnborg noticed that mach-pxa/am200epd.c has a notifier too,
and listens to this.

...

Looking at the code it seems to wait for some fb to show up, so that
it can get the framebuffer base address from the fb_info struct. I
suspect his is some firmware fbdev. Then it uses that information to
let the real fbdev driver (metronomefb.c by the looks) get at the
framebuffer memory.

This doesn't looke like it's easy to fix (except by deleting the
entire thing, seems untouched since 2008, we might be able to get away
with that), so let's just stuff a few #ifdef into fb.h and fbmem.c and
cry over them for a bit.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Yisheng Xie <ysxie@foxmail.com>
Cc: Peter Rosin <peda@axentia.se>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: linux-fbdev@vger.kernel.org
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Steve Sakoman <sakoman@gmail.com>
Cc: Steve Sakoman <steve@sakoman.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190528090304.9388-11-daniel.vetter@ffwll.ch

arch/arm/mach-pxa/am200epd.c

@@ -347,8 +347,17 @@ int __init am200_init(void)
 {
 	int ret;
 
-	/* before anything else, we request notification for any fb
-	 * creation events */
+	/*
+	 * Before anything else, we request notification for any fb
+	 * creation events.
+	 *
+	 * FIXME: This is terrible and needs to be nuked. The notifier is used
+	 * to get at the fb base address from the boot splash fb driver, which
+	 * is then passed to metronomefb. Instaed of metronomfb or this board
+	 * support file here figuring this out on their own.
+	 *
+	 * See also the #ifdef in fbmem.c.
+	 */
 	fb_register_client(&am200_fb_notif);
 
 	pxa2xx_mfp_config(ARRAY_AND_SIZE(am200_pin_config));

drivers/video/fbdev/core/fbcon.c

@@ -3119,14 +3119,14 @@ static int fbcon_fb_unbind(int idx)
 }
 
 /* called with console_lock held */
-static int fbcon_fb_unregistered(struct fb_info *info)
+void fbcon_fb_unregistered(struct fb_info *info)
 {
 	int i, idx;
 
 	WARN_CONSOLE_UNLOCKED();
 
 	if (deferred_takeover)
-		return 0;
+		return;
 
 	idx = info->node;
 	for (i = first_fb_vc; i <= last_fb_vc; i++) {
@@ -3155,8 +3155,6 @@ static int fbcon_fb_unregistered(struct fb_info *info)
 
 	if (!num_registered_fb)
 		do_unregister_con_driver(&fb_con);
-
-	return 0;
 }
 
 /* called with console_lock held */
@@ -3215,7 +3213,7 @@ static inline void fbcon_select_primary(struct fb_info *info)
 #endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */
 
 /* called with console_lock held */
-static int fbcon_fb_registered(struct fb_info *info)
+int fbcon_fb_registered(struct fb_info *info)
 {
 	int ret = 0, i, idx;
 
@@ -3359,12 +3357,6 @@ static int fbcon_event_notify(struct notifier_block *self,
 		idx = info->node;
 		ret = fbcon_fb_unbind(idx);
 		break;
-	case FB_EVENT_FB_REGISTERED:
-		ret = fbcon_fb_registered(info);
-		break;
-	case FB_EVENT_FB_UNREGISTERED:
-		ret = fbcon_fb_unregistered(info);
-		break;
 	case FB_EVENT_SET_CONSOLE_MAP:
 		/* called with console lock held */
 		con2fb = event->data;

drivers/video/fbdev/core/fbmem.c

@@ -1660,7 +1660,6 @@ MODULE_PARM_DESC(lockless_register_fb,
 static int do_register_framebuffer(struct fb_info *fb_info)
 {
 	int i, ret;
-	struct fb_event event;
 	struct fb_videomode mode;
 
 	if (fb_check_foreignness(fb_info))
@@ -1723,7 +1722,14 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	fb_add_videomode(&mode, &fb_info->modelist);
 	registered_fb[i] = fb_info;
 
-	event.info = fb_info;
+#ifdef CONFIG_GUMSTIX_AM200EPD
+	{
+		struct fb_event event;
+		event.info = fb_info;
+		fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+	}
+#endif
+
 	if (!lockless_register_fb)
 		console_lock();
 	else
@@ -1732,9 +1738,8 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 		ret = -ENODEV;
 		goto unlock_console;
 	}
-	ret = 0;
 
-	fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+	ret = fbcon_fb_registered(fb_info);
 	unlock_fb_info(fb_info);
 unlock_console:
 	if (!lockless_register_fb)
@@ -1771,7 +1776,6 @@ static int __unlink_framebuffer(struct fb_info *fb_info);
 
 static int do_unregister_framebuffer(struct fb_info *fb_info)
 {
-	struct fb_event event;
 	int ret;
 
 	ret = unbind_console(fb_info);
@@ -1789,9 +1793,15 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
 	registered_fb[fb_info->node] = NULL;
 	num_registered_fb--;
 	fb_cleanup_device(fb_info);
-	event.info = fb_info;
+#ifdef CONFIG_GUMSTIX_AM200EPD
+	{
+		struct fb_event event;
+		event.info = fb_info;
+		fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+	}
+#endif
 	console_lock();
-	fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+	fbcon_fb_unregistered(fb_info);
 	console_unlock();
 
 	/* this may free fb info */

include/linux/fb.h

@@ -136,10 +136,13 @@ struct fb_cursor_user {
 #define FB_EVENT_RESUME			0x03
 /*      An entry from the modelist was removed */
 #define FB_EVENT_MODE_DELETE            0x04
-/*      A driver registered itself */
+
+#ifdef CONFIG_GUMSTIX_AM200EPD
+/* only used by mach-pxa/am200epd.c */
 #define FB_EVENT_FB_REGISTERED          0x05
-/*      A driver unregistered itself */
 #define FB_EVENT_FB_UNREGISTERED        0x06
+#endif
+
 /*      CONSOLE-SPECIFIC: get console to framebuffer mapping */
 #define FB_EVENT_GET_CONSOLE_MAP        0x07
 /*      CONSOLE-SPECIFIC: set console to framebuffer mapping */

include/linux/fbcon.h

@@ -4,9 +4,13 @@
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE
 void __init fb_console_init(void);
 void __exit fb_console_exit(void);
+int fbcon_fb_registered(struct fb_info *info);
+void fbcon_fb_unregistered(struct fb_info *info);
 #else
 static inline void fb_console_init(void) {}
 static inline void fb_console_exit(void) {}
+static inline int fbcon_fb_registered(struct fb_info *info) { return 0; }
+static inline void fbcon_fb_unregistered(struct fb_info *info) {}
 #endif
 
 #endif /* _LINUX_FBCON_H */