[PATCH] fbdev: video mode change notify (fbset)

From: "Antonino A. Daplas" <adaplas@hotpop.com>

This patch allows fbset to change the video mode and the console window
size via the notifier call chain.  It will only notify fbcon of mode
changes from user space.  Changes coming from upstream will be ignored.

The code will only update the current console.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/console/fbcon.c

@@ -2358,6 +2358,56 @@ static void fbcon_resumed(struct fb_info *info)
 	update_screen(vc->vc_num);
 }
 
+static void fbcon_modechanged(struct fb_info *info)
+{
+	struct vc_data *vc = vc_cons[info->currcon].d;
+	struct display *p;
+	int rows, cols;
+
+	if (info->currcon < 0 || vt_cons[info->currcon]->vc_mode !=
+	    KD_TEXT)
+		return;
+	p = &fb_display[vc->vc_num];
+
+	info->var.xoffset = info->var.yoffset = p->yscroll = 0;
+	vc->vc_can_do_color = info->var.bits_per_pixel != 1;
+	vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
+
+	if (CON_IS_VISIBLE(vc)) {
+		cols = info->var.xres / vc->vc_font.width;
+		rows = info->var.yres / vc->vc_font.height;
+		vc_resize(vc->vc_num, cols, rows);
+		switch (p->scrollmode) {
+		case SCROLL_WRAP:
+			scrollback_phys_max = p->vrows - vc->vc_rows;
+			break;
+		case SCROLL_PAN:
+			scrollback_phys_max = p->vrows - 2 * vc->vc_rows;
+			if (scrollback_phys_max < 0)
+				scrollback_phys_max = 0;
+			break;
+		default:
+			scrollback_phys_max = 0;
+			break;
+		}
+		scrollback_max = 0;
+		scrollback_current = 0;
+		update_var(vc->vc_num, info);
+		fbcon_set_palette(vc, color_table);
+		update_screen(vc->vc_num);
+		if (softback_buf) {
+			int l = fbcon_softback_size / vc->vc_size_row;
+			if (l > 5)
+				softback_end = softback_buf + l * vc->vc_size_row;
+			else {
+				/* Smaller scrollback makes no sense, and 0
+				   would screw the operation totally */
+				softback_top = 0;
+			}
+		}
+	}
+}
+
 static int fbcon_event_notify(struct notifier_block *self, 
 			      unsigned long action, void *data)
 {
@@ -2370,6 +2420,9 @@ static int fbcon_event_notify(struct notifier_block *self,
 	case FB_EVENT_RESUME:
 		fbcon_resumed(info);
 		break;
+	case FB_EVENT_MODE_CHANGE:
+		fbcon_modechanged(info);
+		break;
 	}
 
 	return 0;

drivers/video/fbmem.c

@@ -1005,7 +1005,11 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 
 			fb_set_cmap(&info->cmap, 1, info);
 
-			notifier_call_chain(&fb_notifier_list, FB_EVENT_MODE_CHANGE, info);
+			if (info->flags & FBINFO_MISC_MODECHANGEUSER) {
+				notifier_call_chain(&fb_notifier_list,
+						    FB_EVENT_MODE_CHANGE, info);
+				info->flags &= ~FBINFO_MISC_MODECHANGEUSER;
+			}
 		}
 	}
 	return 0;
@@ -1056,7 +1060,9 @@ fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 		if (copy_from_user(&var, (void *) arg, sizeof(var)))
 			return -EFAULT;
 		acquire_console_sem();
+		info->flags |= FBINFO_MISC_MODECHANGEUSER;
 		i = fb_set_var(info, &var);
+		info->flags &= ~FBINFO_MISC_MODECHANGEUSER;
 		release_console_sem();
 		if (i) return i;
 		if (copy_to_user((void *) arg, &var, sizeof(var)))

include/linux/fb.h

@@ -530,6 +530,8 @@ struct fb_ops {
 #define FBINFO_HWACCEL_YPAN		0x2000 /* optional */
 #define FBINFO_HWACCEL_YWRAP		0x4000 /* optional */
 
+#define FBINFO_MISC_MODECHANGEUSER     0x10000 /* mode change request
+						  from userspace */
 
 struct fb_info {
 	int node;