[PATCH] vgacon: no vertical resizing on EGA

EGA boards suck: they mostly have write-only registers.  This is
particularly problematic for the overflow register: for being able to write
to it, we would have to handle vertical sync & such too, which (I'd say)
would potentially break a lot of configurations.  Instead, just disabling
vertical resize for EGA boards is just nice enough (horizontal resize still
works).

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=6106

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Rafal Olearski <olearski@mail2.kim.net.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 35 insertions, 32 deletions

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 12d9329d1408..5a86978537d2 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -509,57 +509,60 @@ 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, max_scan;
+        u8 scanlines_lo = 0, r7 = 0, vsync_end = 0, 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;
-
         vgacon_xres = width * VGA_FONTWIDTH;
         vgacon_yres = height * c->vc_font.height;
-        outb_p(VGA_CRTC_MODE, vga_video_port_reg);
-        mode = inb_p(vga_video_port_val);
+        if (vga_video_type >= VIDEO_TYPE_VGAC) {
+                outb_p(VGA_CRTC_MAX_SCAN, vga_video_port_reg);
+                max_scan = inb_p(vga_video_port_val);
 
-        if (mode & 0x04)
-                scanlines >>= 1;
+                if (max_scan & 0x80)
+                        scanlines <<= 1;
 
-        scanlines -= 1;
-        scanlines_lo = scanlines & 0xff;
+                outb_p(VGA_CRTC_MODE, vga_video_port_reg);
+                mode = inb_p(vga_video_port_val);
 
-        outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
-        r7 = inb_p(vga_video_port_val) & ~0x42;
+                if (mode & 0x04)
+                        scanlines >>= 1;
 
-        if (scanlines & 0x100)
-                r7 |= 0x02;
-        if (scanlines & 0x200)
-                r7 |= 0x40;
+                scanlines -= 1;
+                scanlines_lo = scanlines & 0xff;
 
-        /* deprotect registers */
-        outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
-        vsync_end = inb_p(vga_video_port_val);
-        outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
-        outb_p(vsync_end & ~0x80, vga_video_port_val);
+                outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
+                r7 = inb_p(vga_video_port_val) & ~0x42;
+
+                if (scanlines & 0x100)
+                        r7 |= 0x02;
+                if (scanlines & 0x200)
+                        r7 |= 0x40;
+
+                /* deprotect registers */
+                outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+                vsync_end = inb_p(vga_video_port_val);
+                outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+                outb_p(vsync_end & ~0x80, vga_video_port_val);
+        }
 
         outb_p(VGA_CRTC_H_DISP, vga_video_port_reg);
         outb_p(width - 1, vga_video_port_val);
         outb_p(VGA_CRTC_OFFSET, vga_video_port_reg);
         outb_p(width >> 1, vga_video_port_val);
 
-        outb_p(VGA_CRTC_V_DISP_END, vga_video_port_reg);
-        outb_p(scanlines_lo, vga_video_port_val);
-        outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
-        outb_p(r7,vga_video_port_val);
+        if (vga_video_type >= VIDEO_TYPE_VGAC) {
+                outb_p(VGA_CRTC_V_DISP_END, vga_video_port_reg);
+                outb_p(scanlines_lo, vga_video_port_val);
+                outb_p(VGA_CRTC_OVERFLOW, vga_video_port_reg);
+                outb_p(r7,vga_video_port_val);
 
-        /* reprotect registers */
-        outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
-        outb_p(vsync_end, vga_video_port_val);
+                /* reprotect registers */
+                outb_p(VGA_CRTC_V_SYNC_END, vga_video_port_reg);
+                outb_p(vsync_end, vga_video_port_val);
+        }
 
         spin_unlock_irqrestore(&vga_lock, flags);
-
         return 0;
 }