From 6ea76f3cade4734e73e3da842005820558b8b828 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 27667f4744fc5a0f3e50910e78740bac5670d18b 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 8694ca9beee3..9dcc7280e572 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, -- 2.34.1