From df679cf923acf7703415ef3bdb6737fa048af4ce Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 3 Aug 2015 17:24:11 +0200 Subject: [PATCH] drm/atomic-helpers: Make encoder picking more robust We've had a few issues with atomic where subtle bugs in the encoder picking logic lead to accidental self-stealing of the encoder, resulting in a NULL connector_state->crtc in update_connector_routing and subsequent. Linus applied some duct-tape for an mst regression in commit 8f62f39a77c2333a93463e0c84dfcaa400fdd9fe Author: Linus Torvalds Date: Wed Jul 29 22:18:16 2015 -0700 i915: temporary fix for DP MST docking station NULL pointer dereference But that was incomplete (the code will still oops when debuggin is enabled) and mangled the state even further. So instead WARN and bail out as the more future-proof option. Cc: Theodore Ts'o Cc: Linus Torvalds Reviewed-by: Thierry Reding Reviewed-by: Ander Conselvan de Oliveira Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_atomic_helper.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 8694ca9beee35..9dcc7280e5720 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -234,13 +234,14 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx) } } + if (WARN_ON(!connector_state->crtc)) + return -EINVAL; + connector_state->best_encoder = new_encoder; - if (connector_state->crtc) { - idx = drm_crtc_index(connector_state->crtc); + idx = drm_crtc_index(connector_state->crtc); - crtc_state = state->crtc_states[idx]; - crtc_state->mode_changed = true; - } + crtc_state = state->crtc_states[idx]; + crtc_state->mode_changed = true; DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n", connector->base.id, -- 2.39.5