[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>

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 12d9329..5a86978 100644 (file)
--- 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;
 }