Commit a5c2c0d1 authored by Lyude Paul's avatar Lyude Paul

drm/display/dp_mst: Add nonblocking helpers for DP MST

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: default avatarLyude 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>
Acked-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220817193847.557945-9-lyude@redhat.com
parent 0b4e477e
......@@ -2808,7 +2808,8 @@ 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 = drm_dp_mst_atomic_setup_commit,
};
static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
......@@ -7959,6 +7960,7 @@ 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) {
......@@ -8357,7 +8359,6 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
dc_release_state(dc_state_temp);
}
static int dm_force_atomic_commit(struct drm_connector *connector)
{
int ret = 0;
......
......@@ -4384,12 +4384,16 @@ 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) {
......@@ -4469,11 +4473,15 @@ 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",
......@@ -4492,6 +4500,83 @@ 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
......@@ -5067,6 +5152,9 @@ 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 */
......@@ -5099,6 +5187,7 @@ 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 */
......@@ -5107,6 +5196,10 @@ 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);
}
......
......@@ -7532,6 +7532,7 @@ 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);
......@@ -8600,6 +8601,10 @@ static int intel_initial_commit(struct drm_device *dev)
return ret;
}
static const struct drm_mode_config_helper_funcs intel_mode_config_funcs = {
.atomic_commit_setup = drm_dp_mst_atomic_setup_commit,
};
static void intel_mode_config_init(struct drm_i915_private *i915)
{
struct drm_mode_config *mode_config = &i915->drm.mode_config;
......@@ -8614,6 +8619,7 @@ 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);
......
......@@ -2136,6 +2136,7 @@ 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);
......@@ -2616,6 +2617,11 @@ nv50_disp_func = {
.atomic_state_free = nv50_disp_atomic_state_free,
};
static const struct drm_mode_config_helper_funcs
nv50_disp_helper_func = {
.atomic_commit_setup = drm_dp_mst_atomic_setup_commit,
};
/******************************************************************************
* Init
*****************************************************************************/
......@@ -2699,6 +2705,7 @@ 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;
......
......@@ -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,
......
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