Modify drm_driver::device_is_agp to return a tri-state value to indicate

that a device absolutely is, absolutely is not, or may or may not be
    AGP. Modify the i915 DRM to use this to force all i9x5 devices to be
    "AGP" (even the PCI-e devices).
Reported by: Lukas Hejtmanek

bsd-core/drmP.h

@@ -644,8 +644,10 @@ struct drm_device {
 	 *
 	 * \param dev  DRM device handle
 	 *
-	 * \returns true if the card really is attached to AGP, false
-	 * otherwise.
+	 * \returns 
+	 * One of three values is returned depending on whether or not the
+	 * card is absolutely \b not AGP (return of 0), absolutely \b is AGP
+	 * (return of 1), or may or may not be AGP (return of 2).
 	 */
 	int (*device_is_agp) (struct drm_device * dev);
 

bsd-core/drm_agpsupport.c

@@ -47,9 +47,12 @@ drm_device_is_agp(drm_device_t *dev)
 	u_int8_t ptr, next;
 
 
-	if ( (dev->driver->device_is_agp != NULL)
-	     && ! (*dev->driver->device_is_agp)( dev ) ) {
-		return 0;
+	if ( dev->driver->device_is_agp != NULL ) {
+		int err = (*dev->driver->device_is_agp)( dev );
+	
+		if (err != 2) {
+			return err;
+		}
 	}
 
 	/*

bsd-core/i915_drv.c

@@ -48,6 +48,7 @@ static void i915_configure(drm_device_t *dev)
 	dev->dev_priv_size = 1;	/* No dev_priv */
 	dev->prerelease = i915_driver_prerelease;
 	dev->pretakedown = i915_driver_pretakedown;
+	dev->device_is_agp = i915_driver_device_is_agp,
 	dev->irq_preinstall = i915_driver_irq_preinstall;
 	dev->irq_postinstall = i915_driver_irq_postinstall;
 	dev->irq_uninstall = i915_driver_irq_uninstall;

linux-core/drmP.h

@@ -548,8 +548,10 @@ struct drm_driver {
 	 *
 	 * \param dev  DRM device handle
 	 *
-	 * \returns true if the card really is attached to AGP, false
-	 * otherwise.
+	 * \returns
+	 * One of three values is returned depending on whether or not the
+	 * card is absolutely \b not AGP (return of 0), absolutely \b is AGP
+	 * (return of 1), or may or may not be AGP (return of 2).
 	 */
 	int (*device_is_agp) (struct drm_device * dev);
 
@@ -1028,9 +1030,12 @@ static __inline__ struct drm_map *drm_core_findmap(struct drm_device *dev,
 
 static __inline__ int drm_device_is_agp(drm_device_t *dev)
 {
-	if ( (dev->driver->device_is_agp != NULL)
-	     && ! (*dev->driver->device_is_agp)( dev ) ) {
-		return 0;
+	if ( dev->driver->device_is_agp != NULL ) {
+		int err = (*dev->driver->device_is_agp)( dev );
+	
+		if (err != 2) {
+			return err;
+		}
 	}
 
 	return pci_find_capability(dev->pdev, PCI_CAP_ID_AGP);

linux-core/i915_drv.c

@@ -60,6 +60,7 @@ static struct drm_driver driver = {
 	    DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED,
 	.pretakedown = i915_driver_pretakedown,
 	.prerelease = i915_driver_prerelease,
+	.device_is_agp = i915_driver_device_is_agp,
 	.irq_preinstall = i915_driver_irq_preinstall,
 	.irq_postinstall = i915_driver_irq_postinstall,
 	.irq_uninstall = i915_driver_irq_uninstall,

linux-core/mga_drv.c

@@ -148,8 +148,7 @@ MODULE_LICENSE("GPL and additional rights");
  * \param dev   The device to be tested.
  *
  * \returns
- * If the device is a PCI G450, zero is returned.  Otherwise non-zero is
- * returned.
+ * If the device is a PCI G450, zero is returned.  Otherwise 2 is returned.
  */
 int mga_driver_device_is_agp(drm_device_t * dev)
 {
@@ -176,5 +175,5 @@ int mga_driver_device_is_agp(drm_device_t * dev)
 		return 0;
 	}
 
-	return 1;
+	return 2;
 }

shared-core/i915_dma.c

@@ -726,3 +726,19 @@ drm_ioctl_desc_t i915_ioctls[] = {
 };
 
 int i915_max_ioctl = DRM_ARRAY_SIZE(i915_ioctls);
+
+/**
+ * Determine if the device really is AGP or not.
+ *
+ * All Intel graphics chipsets are treated as AGP, even if they are really
+ * PCI-e.
+ *
+ * \param dev   The device to be tested.
+ *
+ * \returns
+ * A value of 1 is always retured to indictate every i9x5 is AGP.
+ */
+int i915_driver_device_is_agp(drm_device_t * dev)
+{
+	return 1;
+}

shared-core/i915_drv.h

@@ -80,6 +80,7 @@ typedef struct drm_i915_private {
 extern void i915_kernel_lost_context(drm_device_t * dev);
 extern void i915_driver_pretakedown(drm_device_t * dev);
 extern void i915_driver_prerelease(drm_device_t * dev, DRMFILE filp);
+extern int i915_driver_device_is_agp(drm_device_t * dev);
 
 /* i915_irq.c */
 extern int i915_irq_emit(DRM_IOCTL_ARGS);