From 39942fd8ff57c8623451bbfaffe8a184cc8b463a Mon Sep 17 00:00:00 2001 From: Knut Petersen Date: Mon, 12 Dec 2005 22:17:19 -0800 Subject: [PATCH] [PATCH] fbdev: fix switch to KD_TEXT, enhanced version Every framebuffer driver relies on the assumption that the set_par() function of the driver is called before drawing functions and other functions dependent on the hardware state are executed. Whenever you switch from X to a framebuffer console for the very first time, there is a chance that a broken X system has _not_ set the mode to KD_GRAPHICS, thus the vt and framebuffer code executes a screen redraw and several other functions before a set_par() is executed. This is believed to be not a bug of linux but a bug of X/xdm. At least some X releases used by SuSE and Debian show this behaviour. There was a 2nd case, but that has been fixed by Antonino Daplas on 10-dec-2005. This patch allows drivers to set a flag to inform fbcon_switch() that they prefer a set_par() call on every console switch, working around the problems caused by the broken X releases. The flag will be used by the next release of cyblafb and might help other drivers that assume a hardware state different to the one used by X. As the default behaviour does not change, this patch should be acceptable to everybody. Signed-off-by: Knut Petersen Acked-by: "Antonino A. Daplas" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/console/fbcon.c | 3 ++- include/linux/fb.h | 12 ++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 8068d2f7efe..3660e51b261 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -2103,7 +2103,8 @@ static int fbcon_switch(struct vc_data *vc) fb_set_var(info, &var); ops->var = info->var; - if (old_info != NULL && old_info != info) { + if (old_info != NULL && (old_info != info || + info->flags & FBINFO_MISC_ALWAYS_SETPAR)) { if (info->fbops->fb_set_par) info->fbops->fb_set_par(info); fbcon_del_cursor_timer(old_info); diff --git a/include/linux/fb.h b/include/linux/fb.h index 55ccaf3706c..dab3a4decb4 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -732,6 +732,18 @@ struct fb_tile_ops { from userspace */ #define FBINFO_MISC_TILEBLITTING 0x20000 /* use tile blitting */ +/* A driver may set this flag to indicate that it does want a set_par to be + * called every time when fbcon_switch is executed. The advantage is that with + * this flag set you can really be shure that set_par is always called before + * any of the functions dependant on the correct hardware state or altering + * that state, even if you are using some broken X releases. The disadvantage + * is that it introduces unwanted delays to every console switch if set_par + * is slow. It is a good idea to try this flag in the drivers initialization + * code whenever there is a bug report related to switching between X and the + * framebuffer console. + */ +#define FBINFO_MISC_ALWAYS_SETPAR 0x40000 + struct fb_info { int node; int flags; -- 2.41.1