vt/console: try harder to print output when panicing

Jesse's initial patch commit said:

"At panic time (i.e.  when oops_in_progress is set) we should try a bit
harder to update the screen and make sure output gets to the VT, since
some drivers are capable of flipping back to it.

So make sure we try to unblank and update the display if called from a
panic context."

I've enhanced this to add a flag to the vc that console layer can set to
indicate they want this behaviour to occur.  This also adds support to
fbcon for that flag and adds an fb flag for drivers to indicate they want
to use the support.  It enables this for KMS drivers.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: James Simmons <jsimmons@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 3b3f5749af9..26bf7cbfecc 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -283,7 +283,8 @@ static inline int fbcon_is_inactive(struct vc_data *vc, struct fb_info *info)
         struct fbcon_ops *ops = info->fbcon_par;
 
         return (info->state != FBINFO_STATE_RUNNING ||
-                vc->vc_mode != KD_TEXT || ops->graphics);
+                vc->vc_mode != KD_TEXT || ops->graphics) &&
+                !vt_force_oops_output(vc);
 }
 
 static inline int get_color(struct vc_data *vc, struct fb_info *info,
@@ -1073,6 +1074,7 @@ static void fbcon_init(struct vc_data *vc, int init)
         if (p->userfont)
                 charcnt = FNTCHARCNT(p->fontdata);
 
+        vc->vc_panic_force_write = !!(info->flags & FBINFO_CAN_FORCE_OUTPUT);
         vc->vc_can_do_color = (fb_get_color_depth(&info->var, &info->fix)!=1);
         vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
         if (charcnt == 256) {