drm/nouveau: Disable AGP on PowerPC again.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_agp.c b/drivers/gpu/drm/nouveau/nouveau_agp.c
index d28430cd2ba6..6e7a55f93a85 100644
--- a/drivers/gpu/drm/nouveau/nouveau_agp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_agp.c
@@ -47,6 +47,18 @@ nouveau_agp_enabled(struct nouveau_drm *drm)
         if (drm->agp.stat == UNKNOWN) {
                 if (!nouveau_agpmode)
                         return false;
+#ifdef __powerpc__
+                /* Disable AGP by default on all PowerPC machines for
+                 * now -- At least some UniNorth-2 AGP bridges are
+                 * known to be broken: DMA from the host to the card
+                 * works just fine, but writeback from the card to the
+                 * host goes straight to memory untranslated bypassing
+                 * the GATT somehow, making them quite painful to deal
+                 * with...
+                 */
+                if (nouveau_agpmode == -1)
+                        return false;
+#endif
                 return true;
         }