Remove DGA support from the driver.

The xf86DiDGA code required that the scanout buffer always be
mappable, stay be at a fixed address in the aperture and have a
constant size. With frame buffer resizing, the latter two are no
longer true, and with KMS, we'd really prefer to not allow the former.

The only option available to the driver is to completely disable DGA
as the modes code has internal calls to the xf86DiDGA code when
fetching new modes from the hardware.

A fix for the DiDGA code will be added to the X server which will
automatically initialize DGA for mode switching and input, but not
frame buffer access, and not require any driver cooperation.

Thus, the correct solution is for the driver to not call xf86DiDGAInit
at all. For old servers, this eliminates a potential catastrophic
problem where random memory is written by the X server. New servers
will get the DIX-based behaviour automatically.

Signed-off-by: Keith Packard <keithp@keithp.com>

src/i830_driver.c

@@ -2708,11 +2708,6 @@ I830ScreenInit(int scrnIndex, ScreenPtr pScreen, int argc, char **argv)
 
    xf86SetBlackWhitePixels(pScreen);
 
-#ifdef XFreeXDGA
-   if (!pI830->use_drm_mode)
-       xf86DiDGAInit (pScreen, pI830->LinearAddr + pScrn->fbOffset);
-#endif
-
    if (!I830AccelInit(pScreen)) {
       xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
 		 "Hardware acceleration initialization failed\n");