i915: Disable MSI on GM965 (errata says it doesn't work)

Current Intel errata for the GM965 says that using MSI may cause interrupts
to be delayed or lost. The only workaround offered is to not use it.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/i915_dma.c

@@ -844,8 +844,11 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	 * correctly in testing on 945G.
 	 * This may be a side effect of MSI having been made available for PEG
 	 * and the registers being closely associated.
+	 *
+	 * According to chipset errata, on the 965GM, MSI interrupts may
+	 * be lost or delayed
 	 */
-	if (!IS_I945G(dev) && !IS_I945GM(dev))
+	if (!IS_I945G(dev) && !IS_I945GM(dev) && !IS_I965GM(dev))
 		if (pci_enable_msi(dev->pdev))
 			DRM_ERROR("failed to enable MSI\n");