[PATCH] Fix framebuffer console upside-down ywrap scrolling

Whenever ywrap scrolling is selected together with 180 degree screen
rotation, 2.6.15-rc6 and earlier versions are broken.  fb_pan_display()
expects non-negative yoffsets, but ud_update_start() calls it with
yoffsets down to -(yres - font height).  This patch transforms yoffset
to the correct range 0 ...  vyres-1.

Some obviously unneeded parentheses are removed, too.

Verified with cyblafb, should be applied before 2.6.15-final because it
does fix the framebuffer rotation code introduced early in the 2.6.15
release cycle.

Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de>
Acked-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/video/console/fbcon_ud.c b/drivers/video/console/fbcon_ud.c
index c4d7c89212b4..9dd059e8b645 100644
--- a/drivers/video/console/fbcon_ud.c
+++ b/drivers/video/console/fbcon_ud.c
@@ -420,13 +420,15 @@ static void ud_cursor(struct vc_data *vc, struct fb_info *info,
 int ud_update_start(struct fb_info *info)
 {
         struct fbcon_ops *ops = info->fbcon_par;
-        u32 xoffset, yoffset;
+        int xoffset, yoffset;
         u32 vyres = GETVYRES(ops->p->scrollmode, info);
         u32 vxres = GETVXRES(ops->p->scrollmode, info);
         int err;
 
-        xoffset = (vxres - info->var.xres) - ops->var.xoffset;
-        yoffset = (vyres - info->var.yres) - ops->var.yoffset;
+        xoffset = vxres - info->var.xres - ops->var.xoffset;
+        yoffset = vyres - info->var.yres - ops->var.yoffset;
+        if (yoffset < 0)
+                yoffset += vyres;
         ops->var.xoffset = xoffset;
         ops->var.yoffset = yoffset;
         err = fb_pan_display(info, &ops->var);