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drm/dp_mst: Add branch bandwidth validation to MST atomic check

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[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 <lyude@redhat.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Mikita Lipski 2019-11-06 13:11:23 -05:00 committed by Alex Deucher
parent 8afb7e6afa
commit cd82d82cbc
2 changed files with 65 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
drivers/gpu/drm/drm_dp_mst_topology.c
View File

@ -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;

1
include/drm/drm_dp_mst_helper.h
View File

@ -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;
};