From cd82d82cbc0484e47918d3166f356c98f0066db8 Mon Sep 17 00:00:00 2001 From: Mikita Lipski Date: Wed, 6 Nov 2019 13:11:23 -0500 Subject: [PATCH] drm/dp_mst: Add branch bandwidth validation to MST atomic check [why] Adding PBN attribute to drm_dp_vcpi_allocation structure to keep track of how much bandwidth each Port requires. Adding drm_dp_mst_atomic_check_bw_limit to verify that state's bandwidth needs doesn't exceed available bandwidth. The funtion is called in drm_dp_mst_atomic_check after drm_dp_mst_atomic_check_topology_state to fully verify that the proposed topology is supported. v2: Fixing some typos and indenting v3: Return correct error enums if no bw space available Reviewed-by: Lyude Paul Signed-off-by: Mikita Lipski Signed-off-by: Alex Deucher --- drivers/gpu/drm/drm_dp_mst_topology.c | 66 ++++++++++++++++++++++++++- include/drm/drm_dp_mst_helper.h | 1 + 2 files changed, 65 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 9f7e714c51825..c7bea8a957975 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -4125,7 +4125,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, { struct drm_dp_mst_topology_state *topology_state; struct drm_dp_vcpi_allocation *pos, *vcpi = NULL; - int prev_slots, req_slots; + int prev_slots, prev_bw, req_slots; topology_state = drm_atomic_get_mst_topology_state(state, mgr); if (IS_ERR(topology_state)) @@ -4136,6 +4136,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, if (pos->port == port) { vcpi = pos; prev_slots = vcpi->vcpi; + prev_bw = vcpi->pbn; /* * This should never happen, unless the driver tries @@ -4151,8 +4152,10 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, break; } } - if (!vcpi) + if (!vcpi) { prev_slots = 0; + prev_bw = 0; + } if (pbn_div <= 0) pbn_div = mgr->pbn_div; @@ -4162,6 +4165,9 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n", port->connector->base.id, port->connector->name, port, prev_slots, req_slots); + DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n", + port->connector->base.id, port->connector->name, + port, prev_bw, pbn); /* Add the new allocation to the state */ if (!vcpi) { @@ -4174,6 +4180,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, list_add(&vcpi->next, &topology_state->vcpis); } vcpi->vcpi = req_slots; + vcpi->pbn = pbn; return req_slots; } @@ -4750,6 +4757,58 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj, kfree(mst_state); } +static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port, + struct drm_dp_mst_branch *branch) +{ + while (port->parent) { + if (port->parent == branch) + return true; + + if (port->parent->port_parent) + port = port->parent->port_parent; + else + break; + } + return false; +} + +static inline +int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch, + struct drm_dp_mst_topology_state *mst_state) +{ + struct drm_dp_mst_port *port; + struct drm_dp_vcpi_allocation *vcpi; + int pbn_limit = 0, pbn_used = 0; + + list_for_each_entry(port, &branch->ports, next) { + if (port->mstb) + if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state)) + return -ENOSPC; + + if (port->available_pbn > 0) + pbn_limit = port->available_pbn; + } + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch has %d PBN available\n", + branch, pbn_limit); + + list_for_each_entry(vcpi, &mst_state->vcpis, next) { + if (!vcpi->pbn) + continue; + + if (drm_dp_mst_port_downstream_of_branch(vcpi->port, branch)) + pbn_used += vcpi->pbn; + } + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch used %d PBN\n", + branch, pbn_used); + + if (pbn_used > pbn_limit) { + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] No available bandwidth\n", + branch); + return -ENOSPC; + } + return 0; +} + static inline int drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_topology_state *mst_state) @@ -4881,6 +4940,9 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state) ret = drm_dp_mst_atomic_check_topology_state(mgr, mst_state); if (ret) break; + ret = drm_dp_mst_atomic_check_bw_limit(mgr->mst_primary, mst_state); + if (ret) + break; } return ret; diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index 14ccda19d9cc0..d940f45c76373 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -502,6 +502,7 @@ struct drm_dp_payload { struct drm_dp_vcpi_allocation { struct drm_dp_mst_port *port; int vcpi; + int pbn; bool dsc_enabled; struct list_head next; };