drm/atomic: shutdown *current* encoder

In disable_outputs() we need to shut down the outgoing encoder, not the
incoming one (we have already swapped-state at this point).  Without
this, we end up telling the driver to crtc->dpms(OFF) without first
encoder->dpms(OFF), and that makes some hw quite unhappy.

v2: missing WARN_ON() hunk and comment

Reviewed-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 3a74e81a78df..a17b8e9c0a81 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -499,9 +499,12 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
                 if (!old_conn_state || !old_conn_state->crtc)
                         continue;
 
-                encoder = connector->state->best_encoder;
+                encoder = old_conn_state->best_encoder;
 
-                if (!encoder)
+                /* We shouldn't get this far if we didn't previously have
+                 * an encoder.. but WARN_ON() rather than explode.
+                 */
+                if (WARN_ON(!encoder))
                         continue;
 
                 funcs = encoder->helper_private;