From a5c2c0d164e96d24f73faffcd3b7bbb607e701a9 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Wed, 17 Aug 2022 15:38:37 -0400 Subject: drm/display/dp_mst: Add nonblocking helpers for DP MST MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit As Daniel Vetter pointed out, if we only use the atomic modesetting locks with MST it's technically possible for a driver with non-blocking modesets to race when it comes to MST displays - as we make the mistake of not doing our own CRTC commit tracking in the topology_state object. This could potentially cause problems if something like this happens: * User starts non-blocking commit to disable CRTC-1 on MST topology 1 * User starts non-blocking commit to enable CRTC-2 on MST topology 1 There's no guarantee here that the commit for disabling CRTC-2 will only occur after CRTC-1 has finished, since neither commit shares a CRTC - only the private modesetting object for MST. Keep in mind this likely isn't a problem for blocking modesets, only non-blocking. So, begin fixing this by keeping track of which CRTCs on a topology have changed by keeping track of which CRTCs we release or allocate timeslots on. As well, add some helpers for: * Setting up the drm_crtc_commit structs in the ->commit_setup hook * Waiting for any CRTC dependencies from the previous topology state v2: * Use drm_dp_mst_atomic_setup_commit() directly - Jani Signed-off-by: Lyude Paul Cc: Wayne Lin Cc: Ville Syrjälä Cc: Fangzhi Zuo Cc: Jani Nikula Cc: Imre Deak Cc: Daniel Vetter Cc: Sean Paul Acked-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20220817193847.557945-9-lyude@redhat.com --- include/drm/display/drm_dp_mst_helper.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/drm') diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h index 3b155ad3eee4..0ef7d0e6cf0c 100644 --- a/include/drm/display/drm_dp_mst_helper.h +++ b/include/drm/display/drm_dp_mst_helper.h @@ -581,6 +581,19 @@ struct drm_dp_mst_topology_state { /** @mgr: The topology manager */ struct drm_dp_mst_topology_mgr *mgr; + /** + * @pending_crtc_mask: A bitmask of all CRTCs this topology state touches, drivers may + * modify this to add additional dependencies if needed. + */ + u32 pending_crtc_mask; + /** + * @commit_deps: A list of all CRTC commits affecting this topology, this field isn't + * populated until drm_dp_mst_atomic_wait_for_dependencies() is called. + */ + struct drm_crtc_commit **commit_deps; + /** @num_commit_deps: The number of CRTC commits in @commit_deps */ + size_t num_commit_deps; + /** @total_avail_slots: The total number of slots this topology can handle (63 or 64) */ u8 total_avail_slots; /** @start_slot: The first usable time slot in this topology (1 or 0) */ @@ -890,6 +903,8 @@ int __must_check drm_dp_atomic_release_time_slots(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port); +void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state); +int __must_check drm_dp_mst_atomic_setup_commit(struct drm_atomic_state *state); int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, bool power_up); int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr, -- cgit v1.2.3