Merge tag 'imx-drm-fixes-2016-11-10' of git://git.pengutronix.de/git/…

…pza/linux into drm-fixes

imx-drm: fix possible hangup when disabling crtcs

- only ever disable the display controller (DC) module after all plane
  IDMAC channels are stopped. This fixes a regression introduced by the
  atomic modeset conversion.

* tag 'imx-drm-fixes-2016-11-10' of git://git.pengutronix.de/git/pza/linux:
  drm/imx: disable planes before DC

drivers/gpu/drm/imx/ipuv3-crtc.c

@@ -68,6 +68,12 @@ static void ipu_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	ipu_dc_disable_channel(ipu_crtc->dc);
 	ipu_di_disable(ipu_crtc->di);
+	/*
+	 * Planes must be disabled before DC clock is removed, as otherwise the
+	 * attached IDMACs will be left in undefined state, possibly hanging
+	 * the IPU or even system.
+	 */
+	drm_atomic_helper_disable_planes_on_crtc(old_crtc_state, false);
 	ipu_dc_disable(ipu);
 
 	spin_lock_irq(&crtc->dev->event_lock);
@@ -77,9 +83,6 @@ static void ipu_crtc_atomic_disable(struct drm_crtc *crtc,
 	}
 	spin_unlock_irq(&crtc->dev->event_lock);
 
-	/* always disable planes on the CRTC */
-	drm_atomic_helper_disable_planes_on_crtc(old_crtc_state, true);
-
 	drm_crtc_vblank_off(crtc);
 }