Commit cd82d82c authored by Mikita Lipski's avatar Mikita Lipski Committed by Alex Deucher
Browse files

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: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarMikita Lipski <mikita.lipski@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 8afb7e6a

drivers/gpu/drm/drm_dp_mst_topology.c

+64 −2
Original line number Diff line number Diff line
@@ -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;

include/drm/drm_dp_mst_helper.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

};

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