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