Tilting allows using left/right rotated or invetrted display orientation.
This can be changed at runtime such as: echo tilt right > /dev/vgactl
This removes the old panning and vga overlays as they are only implemented
with some ancient vga controllers.
devmouse controls the screen blanking timeout, so move the
code there avoiding cross calls between modules. the only
function that needs to be provided is blankscreen(), which
gets called with drawlock locked.
the blank timeout is set thru /dev/mousectl now, so kernels
without devvga can set it.
blanking now only happens while /dev/mouse is read. so this
avoids accidentally blanking the screen on cpu servers that
do not have a mouse to unblank it.
At least on some NVIDIA cards the default scaling mode makes
black borders visible on all sides, even on native resolution.
This patch adds a generic "scaling MODE" command to vgactl
and adds support for it on VESA through NVIDIA VBE OEM extension.
It hasn't been tested on any other video cards, but shouldn't
break anything as the scaling mode is only set on write to vgactl.
allow the shadow framebuffer (softscreen) to be used with any
vga driver, not just vesa. this removes the ugly scr->paddr = 0
hack employed by vesa driver to force softscreen and adds a
softscreen vgactl message that can switch the feature on and off
at runtime.
softscreen can greatly improve graphics performance when bus
reads are slow even tho it disables hardware acceleration.
