fbdev: advertise limitation of drawing engine

A few drivers are not capable of blitting rectangles of any dimension.
vga16fb can only blit 8-pixel wide rectangles, while s3fb (in tileblitting
mode) can only blit 8x16 rectangles.  For example, loading a 12x22 font in
vga16fb will result in a corrupt display.

Advertise this limitation/capability in info->pixmap.blit_x and blit_y.  These
fields are 32-bit arrays (font max is 32x32 only), ie, if bit 7 is set, then
width/height of 7+1 is supported.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 7b72841222df..c4ce3e44327e 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1321,6 +1321,12 @@ register_framebuffer(struct fb_info *fb_info)
         }       
         fb_info->pixmap.offset = 0;
 
+        if (!fb_info->pixmap.blit_x)
+                fb_info->pixmap.blit_x = ~(u32)0;
+
+        if (!fb_info->pixmap.blit_y)
+                fb_info->pixmap.blit_y = ~(u32)0;
+
         if (!fb_info->modelist.prev || !fb_info->modelist.next)
                 INIT_LIST_HEAD(&fb_info->modelist);