CL_GR31
vga_wgfx(cinfo->regbase, CL_GR31, 0x00);
vga_wgfx(cinfo->regbase, CL_GR31, 0x04);
vga_wgfx(cinfo->regbase, CL_GR31, 0x00);
while (vga_rgfx(cinfo->regbase, CL_GR31) & 0x03)
while (vga_rgfx(regbase, CL_GR31) & 0x08)
vga_wgfx(regbase, CL_GR31, 0x02); /* BLT Start/status */