[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 <Knut_Petersen@t-online.de>
Acked-by: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 55ccaf3..dab3a4d 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -732,6 +732,18 @@
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;