[PATCH] vgacon: fix doublescan mode

When doublescan mode is in use, scanlines must be doubled.

Thanks to Jason Dravet <dravet@hotmail.com> for reporting and testing.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 167de397e4b4..f4e1c4b4191e 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -503,10 +503,16 @@ static int vgacon_doresize(struct vc_data *c,
 {
         unsigned long flags;
         unsigned int scanlines = height * c->vc_font.height;
-        u8 scanlines_lo, r7, vsync_end, mode;
+        u8 scanlines_lo, r7, vsync_end, mode, max_scan;
 
         spin_lock_irqsave(&vga_lock, flags);
 
+        outb_p(VGA_CRTC_MAX_SCAN, vga_video_port_reg);
+        max_scan = inb_p(vga_video_port_val);
+
+        if (max_scan & 0x80)
+                scanlines <<= 1;
+
         outb_p(VGA_CRTC_MODE, vga_video_port_reg);
         mode = inb_p(vga_video_port_val);