drm: add test for AGP devices and driver override for it.

Added device_is_agp callback to drm_driver.  This function is called by the
platform-specific drm_device_is_agp function.  Added implementation of this
function the the Linux-specific portion of the MGA driver to detect PCI G450
cards.  Added code to the Linux-specific portion of the generic DRM layer to
not initialize AGP infrastructure if the card is not AGP (this matches what
already existed in BSD).

Fix up i810/i830 and i915 drivers to always return AGP as they don't always
report the capability.

Fix the MGA to not report AGP for a card that has an AGP chip behind a PCI
bridge.

From: Ian Romanick, Dave Airlie, Alan Hourihane
Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/char/drm/drm_stub.c b/drivers/char/drm/drm_stub.c
index 48829a1a086a..068ca9a8b0b4 100644
--- a/drivers/char/drm/drm_stub.c
+++ b/drivers/char/drm/drm_stub.c
@@ -91,7 +91,8 @@ static int drm_fill_in_dev(drm_device_t *dev, struct pci_dev *pdev, const struct
                         goto error_out_unreg;
 
         if (drm_core_has_AGP(dev)) {
-                dev->agp = drm_agp_init(dev);
+                if (drm_device_is_agp(dev))
+                        dev->agp = drm_agp_init(dev);
                 if (drm_core_check_feature(dev, DRIVER_REQUIRE_AGP) && (dev->agp == NULL)) {
                         DRM_ERROR( "Cannot initialize the agpgart module.\n" );
                         retcode = -EINVAL;