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
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Wayne Lin Wayne.Lin@amd.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Fangzhi Zuo Jerry.Zuo@amd.com Cc: Jani Nikula jani.nikula@intel.com Cc: Imre Deak imre.deak@intel.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Sean Paul sean@poorly.run --- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 9 +- drivers/gpu/drm/display/drm_dp_mst_topology.c | 93 +++++++++++++++++++ drivers/gpu/drm/i915/display/intel_display.c | 11 +++ drivers/gpu/drm/nouveau/dispnv50/disp.c | 12 +++ include/drm/display/drm_dp_mst_helper.h | 15 +++ 5 files changed, 139 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index f84a4ad736d8..d9c7393ef151 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -211,6 +211,7 @@ static int amdgpu_dm_encoder_init(struct drm_device *dev, static int amdgpu_dm_connector_get_modes(struct drm_connector *connector);
static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state); +static int amdgpu_dm_atomic_setup_commit(struct drm_atomic_state *state);
static int amdgpu_dm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state); @@ -2808,7 +2809,8 @@ static const struct drm_mode_config_funcs amdgpu_dm_mode_funcs = { };
static struct drm_mode_config_helper_funcs amdgpu_dm_mode_config_helperfuncs = { - .atomic_commit_tail = amdgpu_dm_atomic_commit_tail + .atomic_commit_tail = amdgpu_dm_atomic_commit_tail, + .atomic_commit_setup = amdgpu_dm_atomic_setup_commit, };
static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector) @@ -9558,6 +9560,7 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state) DRM_ERROR("Waiting for fences timed out!");
drm_atomic_helper_update_legacy_modeset_state(dev, state); + drm_dp_mst_atomic_wait_for_dependencies(state);
dm_state = dm_atomic_get_new_state(state); if (dm_state && dm_state->context) { @@ -9958,6 +9961,10 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state) dc_release_state(dc_state_temp); }
+static int amdgpu_dm_atomic_setup_commit(struct drm_atomic_state *state) +{ + return drm_dp_mst_atomic_setup_commit(state); +}
static int dm_force_atomic_commit(struct drm_connector *connector) { diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 0bc2c7a90c37..a0ed29f83556 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -4395,12 +4395,16 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state, { struct drm_dp_mst_topology_state *topology_state; struct drm_dp_mst_atomic_payload *payload = NULL; + struct drm_connector_state *conn_state; int prev_slots = 0, prev_bw = 0, req_slots;
topology_state = drm_atomic_get_mst_topology_state(state, mgr); if (IS_ERR(topology_state)) return PTR_ERR(topology_state);
+ conn_state = drm_atomic_get_new_connector_state(state, port->connector); + topology_state->pending_crtc_mask |= drm_crtc_mask(conn_state->crtc); + /* Find the current allocation for this port, if any */ payload = drm_atomic_get_mst_payload_state(topology_state, port); if (payload) { @@ -4480,11 +4484,15 @@ int drm_dp_atomic_release_time_slots(struct drm_atomic_state *state, { struct drm_dp_mst_topology_state *topology_state; struct drm_dp_mst_atomic_payload *payload; + struct drm_connector_state *conn_state;
topology_state = drm_atomic_get_mst_topology_state(state, mgr); if (IS_ERR(topology_state)) return PTR_ERR(topology_state);
+ conn_state = drm_atomic_get_old_connector_state(state, port->connector); + topology_state->pending_crtc_mask |= drm_crtc_mask(conn_state->crtc); + payload = drm_atomic_get_mst_payload_state(topology_state, port); if (WARN_ON(!payload)) { drm_err(mgr->dev, "No payload for [MST PORT:%p] found in mst state %p\n", @@ -4503,6 +4511,83 @@ int drm_dp_atomic_release_time_slots(struct drm_atomic_state *state, } EXPORT_SYMBOL(drm_dp_atomic_release_time_slots);
+/** + * drm_dp_mst_atomic_setup_commit() - setup_commit hook for MST helpers + * @state: global atomic state + * + * This function saves all of the &drm_crtc_commit structs in an atomic state that touch any CRTCs + * currently assigned to an MST topology. Drivers must call this hook from their + * &drm_mode_config_helper_funcs.atomic_commit_setup hook. + * + * Returns: + * 0 if all CRTC commits were retrieved successfully, negative error code otherwise + */ +int drm_dp_mst_atomic_setup_commit(struct drm_atomic_state *state) +{ + struct drm_dp_mst_topology_mgr *mgr; + struct drm_dp_mst_topology_state *mst_state; + struct drm_crtc *crtc; + struct drm_crtc_state *crtc_state; + int i, j, commit_idx, num_commit_deps; + + for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) { + if (!mst_state->pending_crtc_mask) + continue; + + num_commit_deps = hweight32(mst_state->pending_crtc_mask); + mst_state->commit_deps = kmalloc_array(num_commit_deps, + sizeof(*mst_state->commit_deps), GFP_KERNEL); + if (!mst_state->commit_deps) + return -ENOMEM; + mst_state->num_commit_deps = num_commit_deps; + + commit_idx = 0; + for_each_new_crtc_in_state(state, crtc, crtc_state, j) { + if (mst_state->pending_crtc_mask & drm_crtc_mask(crtc)) { + mst_state->commit_deps[commit_idx++] = + drm_crtc_commit_get(crtc_state->commit); + } + } + } + + return 0; +} +EXPORT_SYMBOL(drm_dp_mst_atomic_setup_commit); + +/** + * drm_dp_mst_atomic_wait_for_dependencies() - Wait for all pending commits on MST topologies + * @state: global atomic state + * + * Goes through any MST topologies in this atomic state, and waits for any pending commits which + * touched CRTCs that were/are on an MST topology to be programmed to hardware and flipped to before + * returning. This is to prevent multiple non-blocking commits affecting an MST topology from racing + * with eachother by forcing them to be executed sequentially in situations where the only resources + * the modeset objects in these commits share are an MST topology. + * + * This function also prepares the new MST state for commit by performing some state preparation + * which can't be done until this point, such as reading back the final VC start slots (which are + * determined at commit-time) from the previous state. + * + * All MST drivers must call this function after calling drm_atomic_helper_wait_for_dependencies(), + * or whatever their equivalent of that is. + */ +void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state) +{ + struct drm_dp_mst_topology_state *old_mst_state; + struct drm_dp_mst_topology_mgr *mgr; + int i, j, ret; + + for_each_old_mst_mgr_in_state(state, mgr, old_mst_state, i) { + for (j = 0; j < old_mst_state->num_commit_deps; j++) { + ret = drm_crtc_commit_wait(old_mst_state->commit_deps[j]); + if (ret < 0) + drm_err(state->dev, "Failed to wait for %s: %d\n", + old_mst_state->commit_deps[j]->crtc->name, ret); + } + } +} +EXPORT_SYMBOL(drm_dp_mst_atomic_wait_for_dependencies); + /** * drm_dp_mst_update_slots() - updates the slot info depending on the DP ecoding format * @mst_state: mst_state to update @@ -5079,6 +5164,9 @@ drm_dp_mst_duplicate_state(struct drm_private_obj *obj) __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
INIT_LIST_HEAD(&state->payloads); + state->commit_deps = NULL; + state->num_commit_deps = 0; + state->pending_crtc_mask = 0;
list_for_each_entry(pos, &old_state->payloads, next) { /* Prune leftover freed timeslot allocations */ @@ -5111,6 +5199,7 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj, struct drm_dp_mst_topology_state *mst_state = to_dp_mst_topology_state(state); struct drm_dp_mst_atomic_payload *pos, *tmp; + int i;
list_for_each_entry_safe(pos, tmp, &mst_state->payloads, next) { /* We only keep references to ports with non-zero VCPIs */ @@ -5119,6 +5208,10 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj, kfree(pos); }
+ for (i = 0; i < mst_state->num_commit_deps; i++) + drm_crtc_commit_put(mst_state->commit_deps[i]); + + kfree(mst_state->commit_deps); kfree(mst_state); }
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index 186b37925d23..5475f66c0ed8 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -8446,6 +8446,7 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state) intel_atomic_commit_fence_wait(state);
drm_atomic_helper_wait_for_dependencies(&state->base); + drm_dp_mst_atomic_wait_for_dependencies(&state->base);
if (state->modeset) wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_MODESET); @@ -9514,6 +9515,15 @@ static int intel_initial_commit(struct drm_device *dev) return ret; }
+static int intel_atomic_commit_setup(struct drm_atomic_state *state) +{ + return drm_dp_mst_atomic_setup_commit(state); +} + +static const struct drm_mode_config_helper_funcs intel_mode_config_funcs = { + .atomic_commit_setup = intel_atomic_commit_setup, +}; + static void intel_mode_config_init(struct drm_i915_private *i915) { struct drm_mode_config *mode_config = &i915->drm.mode_config; @@ -9528,6 +9538,7 @@ static void intel_mode_config_init(struct drm_i915_private *i915) mode_config->prefer_shadow = 1;
mode_config->funcs = &intel_mode_funcs; + mode_config->helper_private = &intel_mode_config_funcs;
mode_config->async_page_flip = HAS_ASYNC_FLIPS(i915);
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 631dba5a2418..768312607fdb 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -2134,6 +2134,7 @@ nv50_disp_atomic_commit_tail(struct drm_atomic_state *state) nv50_crc_atomic_stop_reporting(state); drm_atomic_helper_wait_for_fences(dev, state, false); drm_atomic_helper_wait_for_dependencies(state); + drm_dp_mst_atomic_wait_for_dependencies(state); drm_atomic_helper_update_legacy_modeset_state(dev, state); drm_atomic_helper_calc_timestamping_constants(state);
@@ -2614,6 +2615,16 @@ nv50_disp_func = { .atomic_state_free = nv50_disp_atomic_state_free, };
+static int nv50_disp_atomic_setup_commit(struct drm_atomic_state *state) +{ + return drm_dp_mst_atomic_setup_commit(state); +} + +static const struct drm_mode_config_helper_funcs +nv50_disp_helper_func = { + .atomic_commit_setup = nv50_disp_atomic_setup_commit, +}; + /****************************************************************************** * Init *****************************************************************************/ @@ -2713,6 +2724,7 @@ nv50_display_create(struct drm_device *dev) nouveau_display(dev)->fini = nv50_display_fini; disp->disp = &nouveau_display(dev)->disp; dev->mode_config.funcs = &nv50_disp_func; + dev->mode_config.helper_private = &nv50_disp_helper_func; dev->mode_config.quirk_addfb_prefer_xbgr_30bpp = true; dev->mode_config.normalize_zpos = true;
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h index eb0ea578b227..dd74afcee888 100644 --- a/include/drm/display/drm_dp_mst_helper.h +++ b/include/drm/display/drm_dp_mst_helper.h @@ -576,6 +576,19 @@ 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) */ @@ -885,6 +898,8 @@ 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,