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- // SPDX-License-Identifier: MIT
- /*
- * Copyright (C) 2019 Google, Inc.
- *
- * Authors:
- * Sean Paul <seanpaul@chromium.org>
- */
- #include <linux/average.h>
- #include <linux/bitops.h>
- #include <linux/slab.h>
- #include <linux/workqueue.h>
- #include <drm/drm_atomic.h>
- #include <drm/drm_atomic_helper.h>
- #include <drm/drm_connector.h>
- #include <drm/drm_crtc.h>
- #include <drm/drm_device.h>
- #include <drm/drm_mode_config.h>
- #include <drm/drm_modeset_lock.h>
- #include <drm/drm_print.h>
- #include <drm/drm_self_refresh_helper.h>
- /**
- * DOC: overview
- *
- * This helper library provides an easy way for drivers to leverage the atomic
- * framework to implement panel self refresh (SR) support. Drivers are
- * responsible for initializing and cleaning up the SR helpers on load/unload
- * (see &drm_self_refresh_helper_init/&drm_self_refresh_helper_cleanup).
- * The connector is responsible for setting
- * &drm_connector_state.self_refresh_aware to true at runtime if it is SR-aware
- * (meaning it knows how to initiate self refresh on the panel).
- *
- * Once a crtc has enabled SR using &drm_self_refresh_helper_init, the
- * helpers will monitor activity and call back into the driver to enable/disable
- * SR as appropriate. The best way to think about this is that it's a DPMS
- * on/off request with &drm_crtc_state.self_refresh_active set in crtc state
- * that tells you to disable/enable SR on the panel instead of power-cycling it.
- *
- * During SR, drivers may choose to fully disable their crtc/encoder/bridge
- * hardware (in which case no driver changes are necessary), or they can inspect
- * &drm_crtc_state.self_refresh_active if they want to enter low power mode
- * without full disable (in case full disable/enable is too slow).
- *
- * SR will be deactivated if there are any atomic updates affecting the
- * pipe that is in SR mode. If a crtc is driving multiple connectors, all
- * connectors must be SR aware and all will enter/exit SR mode at the same time.
- *
- * If the crtc and connector are SR aware, but the panel connected does not
- * support it (or is otherwise unable to enter SR), the driver should fail
- * atomic_check when &drm_crtc_state.self_refresh_active is true.
- */
- #define SELF_REFRESH_AVG_SEED_MS 200
- DECLARE_EWMA(psr_time, 4, 4)
- struct drm_self_refresh_data {
- struct drm_crtc *crtc;
- struct delayed_work entry_work;
- struct mutex avg_mutex;
- struct ewma_psr_time entry_avg_ms;
- struct ewma_psr_time exit_avg_ms;
- };
- static void drm_self_refresh_helper_entry_work(struct work_struct *work)
- {
- struct drm_self_refresh_data *sr_data = container_of(
- to_delayed_work(work),
- struct drm_self_refresh_data, entry_work);
- struct drm_crtc *crtc = sr_data->crtc;
- struct drm_device *dev = crtc->dev;
- struct drm_modeset_acquire_ctx ctx;
- struct drm_atomic_state *state;
- struct drm_connector *conn;
- struct drm_connector_state *conn_state;
- struct drm_crtc_state *crtc_state;
- int i, ret = 0;
- drm_modeset_acquire_init(&ctx, 0);
- state = drm_atomic_state_alloc(dev);
- if (!state) {
- ret = -ENOMEM;
- goto out_drop_locks;
- }
- retry:
- state->acquire_ctx = &ctx;
- crtc_state = drm_atomic_get_crtc_state(state, crtc);
- if (IS_ERR(crtc_state)) {
- ret = PTR_ERR(crtc_state);
- goto out;
- }
- if (!crtc_state->enable)
- goto out;
- ret = drm_atomic_add_affected_connectors(state, crtc);
- if (ret)
- goto out;
- for_each_new_connector_in_state(state, conn, conn_state, i) {
- if (!conn_state->self_refresh_aware)
- goto out;
- }
- crtc_state->active = false;
- crtc_state->self_refresh_active = true;
- ret = drm_atomic_commit(state);
- if (ret)
- goto out;
- out:
- if (ret == -EDEADLK) {
- drm_atomic_state_clear(state);
- ret = drm_modeset_backoff(&ctx);
- if (!ret)
- goto retry;
- }
- drm_atomic_state_put(state);
- out_drop_locks:
- drm_modeset_drop_locks(&ctx);
- drm_modeset_acquire_fini(&ctx);
- }
- /**
- * drm_self_refresh_helper_update_avg_times - Updates a crtc's SR time averages
- * @state: the state which has just been applied to hardware
- * @commit_time_ms: the amount of time in ms that this commit took to complete
- * @new_self_refresh_mask: bitmask of crtc's that have self_refresh_active in
- * new state
- *
- * Called after &drm_mode_config_funcs.atomic_commit_tail, this function will
- * update the average entry/exit self refresh times on self refresh transitions.
- * These averages will be used when calculating how long to delay before
- * entering self refresh mode after activity.
- */
- void
- drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state,
- unsigned int commit_time_ms,
- unsigned int new_self_refresh_mask)
- {
- struct drm_crtc *crtc;
- struct drm_crtc_state *old_crtc_state;
- int i;
- for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
- bool new_self_refresh_active = new_self_refresh_mask & BIT(i);
- struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
- struct ewma_psr_time *time;
- if (old_crtc_state->self_refresh_active ==
- new_self_refresh_active)
- continue;
- if (new_self_refresh_active)
- time = &sr_data->entry_avg_ms;
- else
- time = &sr_data->exit_avg_ms;
- mutex_lock(&sr_data->avg_mutex);
- ewma_psr_time_add(time, commit_time_ms);
- mutex_unlock(&sr_data->avg_mutex);
- }
- }
- EXPORT_SYMBOL(drm_self_refresh_helper_update_avg_times);
- /**
- * drm_self_refresh_helper_alter_state - Alters the atomic state for SR exit
- * @state: the state currently being checked
- *
- * Called at the end of atomic check. This function checks the state for flags
- * incompatible with self refresh exit and changes them. This is a bit
- * disingenuous since userspace is expecting one thing and we're giving it
- * another. However in order to keep self refresh entirely hidden from
- * userspace, this is required.
- *
- * At the end, we queue up the self refresh entry work so we can enter PSR after
- * the desired delay.
- */
- void drm_self_refresh_helper_alter_state(struct drm_atomic_state *state)
- {
- struct drm_crtc *crtc;
- struct drm_crtc_state *crtc_state;
- int i;
- if (state->async_update || !state->allow_modeset) {
- for_each_old_crtc_in_state(state, crtc, crtc_state, i) {
- if (crtc_state->self_refresh_active) {
- state->async_update = false;
- state->allow_modeset = true;
- break;
- }
- }
- }
- for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
- struct drm_self_refresh_data *sr_data;
- unsigned int delay;
- /* Don't trigger the entry timer when we're already in SR */
- if (crtc_state->self_refresh_active)
- continue;
- sr_data = crtc->self_refresh_data;
- if (!sr_data)
- continue;
- mutex_lock(&sr_data->avg_mutex);
- delay = (ewma_psr_time_read(&sr_data->entry_avg_ms) +
- ewma_psr_time_read(&sr_data->exit_avg_ms)) * 2;
- mutex_unlock(&sr_data->avg_mutex);
- mod_delayed_work(system_wq, &sr_data->entry_work,
- msecs_to_jiffies(delay));
- }
- }
- EXPORT_SYMBOL(drm_self_refresh_helper_alter_state);
- /**
- * drm_self_refresh_helper_init - Initializes self refresh helpers for a crtc
- * @crtc: the crtc which supports self refresh supported displays
- *
- * Returns zero if successful or -errno on failure
- */
- int drm_self_refresh_helper_init(struct drm_crtc *crtc)
- {
- struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
- /* Helper is already initialized */
- if (WARN_ON(sr_data))
- return -EINVAL;
- sr_data = kzalloc(sizeof(*sr_data), GFP_KERNEL);
- if (!sr_data)
- return -ENOMEM;
- INIT_DELAYED_WORK(&sr_data->entry_work,
- drm_self_refresh_helper_entry_work);
- sr_data->crtc = crtc;
- mutex_init(&sr_data->avg_mutex);
- ewma_psr_time_init(&sr_data->entry_avg_ms);
- ewma_psr_time_init(&sr_data->exit_avg_ms);
- /*
- * Seed the averages so they're non-zero (and sufficiently large
- * for even poorly performing panels). As time goes on, this will be
- * averaged out and the values will trend to their true value.
- */
- ewma_psr_time_add(&sr_data->entry_avg_ms, SELF_REFRESH_AVG_SEED_MS);
- ewma_psr_time_add(&sr_data->exit_avg_ms, SELF_REFRESH_AVG_SEED_MS);
- crtc->self_refresh_data = sr_data;
- return 0;
- }
- EXPORT_SYMBOL(drm_self_refresh_helper_init);
- /**
- * drm_self_refresh_helper_cleanup - Cleans up self refresh helpers for a crtc
- * @crtc: the crtc to cleanup
- */
- void drm_self_refresh_helper_cleanup(struct drm_crtc *crtc)
- {
- struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
- /* Helper is already uninitialized */
- if (!sr_data)
- return;
- crtc->self_refresh_data = NULL;
- cancel_delayed_work_sync(&sr_data->entry_work);
- kfree(sr_data);
- }
- EXPORT_SYMBOL(drm_self_refresh_helper_cleanup);
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