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       1                 :            : // SPDX-License-Identifier: MIT
       2                 :            : /*
       3                 :            :  * Copyright (C) 2019 Google, Inc.
       4                 :            :  *
       5                 :            :  * Authors:
       6                 :            :  * Sean Paul <seanpaul@chromium.org>
       7                 :            :  */
       8                 :            : #include <linux/average.h>
       9                 :            : #include <linux/bitops.h>
      10                 :            : #include <linux/slab.h>
      11                 :            : #include <linux/workqueue.h>
      12                 :            : 
      13                 :            : #include <drm/drm_atomic.h>
      14                 :            : #include <drm/drm_atomic_helper.h>
      15                 :            : #include <drm/drm_connector.h>
      16                 :            : #include <drm/drm_crtc.h>
      17                 :            : #include <drm/drm_device.h>
      18                 :            : #include <drm/drm_mode_config.h>
      19                 :            : #include <drm/drm_modeset_lock.h>
      20                 :            : #include <drm/drm_print.h>
      21                 :            : #include <drm/drm_self_refresh_helper.h>
      22                 :            : 
      23                 :            : /**
      24                 :            :  * DOC: overview
      25                 :            :  *
      26                 :            :  * This helper library provides an easy way for drivers to leverage the atomic
      27                 :            :  * framework to implement panel self refresh (SR) support. Drivers are
      28                 :            :  * responsible for initializing and cleaning up the SR helpers on load/unload
      29                 :            :  * (see &drm_self_refresh_helper_init/&drm_self_refresh_helper_cleanup).
      30                 :            :  * The connector is responsible for setting
      31                 :            :  * &drm_connector_state.self_refresh_aware to true at runtime if it is SR-aware
      32                 :            :  * (meaning it knows how to initiate self refresh on the panel).
      33                 :            :  *
      34                 :            :  * Once a crtc has enabled SR using &drm_self_refresh_helper_init, the
      35                 :            :  * helpers will monitor activity and call back into the driver to enable/disable
      36                 :            :  * SR as appropriate. The best way to think about this is that it's a DPMS
      37                 :            :  * on/off request with &drm_crtc_state.self_refresh_active set in crtc state
      38                 :            :  * that tells you to disable/enable SR on the panel instead of power-cycling it.
      39                 :            :  *
      40                 :            :  * During SR, drivers may choose to fully disable their crtc/encoder/bridge
      41                 :            :  * hardware (in which case no driver changes are necessary), or they can inspect
      42                 :            :  * &drm_crtc_state.self_refresh_active if they want to enter low power mode
      43                 :            :  * without full disable (in case full disable/enable is too slow).
      44                 :            :  *
      45                 :            :  * SR will be deactivated if there are any atomic updates affecting the
      46                 :            :  * pipe that is in SR mode. If a crtc is driving multiple connectors, all
      47                 :            :  * connectors must be SR aware and all will enter/exit SR mode at the same time.
      48                 :            :  *
      49                 :            :  * If the crtc and connector are SR aware, but the panel connected does not
      50                 :            :  * support it (or is otherwise unable to enter SR), the driver should fail
      51                 :            :  * atomic_check when &drm_crtc_state.self_refresh_active is true.
      52                 :            :  */
      53                 :            : 
      54                 :            : #define SELF_REFRESH_AVG_SEED_MS 200
      55                 :            : 
      56         [ #  # ]:          0 : DECLARE_EWMA(psr_time, 4, 4)
      57                 :            : 
      58                 :            : struct drm_self_refresh_data {
      59                 :            :         struct drm_crtc *crtc;
      60                 :            :         struct delayed_work entry_work;
      61                 :            : 
      62                 :            :         struct mutex avg_mutex;
      63                 :            :         struct ewma_psr_time entry_avg_ms;
      64                 :            :         struct ewma_psr_time exit_avg_ms;
      65                 :            : };
      66                 :            : 
      67                 :          0 : static void drm_self_refresh_helper_entry_work(struct work_struct *work)
      68                 :            : {
      69                 :          0 :         struct drm_self_refresh_data *sr_data = container_of(
      70                 :            :                                 to_delayed_work(work),
      71                 :            :                                 struct drm_self_refresh_data, entry_work);
      72                 :          0 :         struct drm_crtc *crtc = sr_data->crtc;
      73                 :          0 :         struct drm_device *dev = crtc->dev;
      74                 :          0 :         struct drm_modeset_acquire_ctx ctx;
      75                 :          0 :         struct drm_atomic_state *state;
      76                 :          0 :         struct drm_connector *conn;
      77                 :          0 :         struct drm_connector_state *conn_state;
      78                 :          0 :         struct drm_crtc_state *crtc_state;
      79                 :          0 :         int i, ret = 0;
      80                 :            : 
      81                 :          0 :         drm_modeset_acquire_init(&ctx, 0);
      82                 :            : 
      83                 :          0 :         state = drm_atomic_state_alloc(dev);
      84         [ #  # ]:          0 :         if (!state) {
      85                 :          0 :                 ret = -ENOMEM;
      86                 :          0 :                 goto out_drop_locks;
      87                 :            :         }
      88                 :            : 
      89                 :          0 : retry:
      90                 :          0 :         state->acquire_ctx = &ctx;
      91                 :            : 
      92                 :          0 :         crtc_state = drm_atomic_get_crtc_state(state, crtc);
      93         [ #  # ]:          0 :         if (IS_ERR(crtc_state)) {
      94                 :          0 :                 ret = PTR_ERR(crtc_state);
      95                 :          0 :                 goto out;
      96                 :            :         }
      97                 :            : 
      98         [ #  # ]:          0 :         if (!crtc_state->enable)
      99                 :          0 :                 goto out;
     100                 :            : 
     101                 :          0 :         ret = drm_atomic_add_affected_connectors(state, crtc);
     102         [ #  # ]:          0 :         if (ret)
     103                 :          0 :                 goto out;
     104                 :            : 
     105   [ #  #  #  # ]:          0 :         for_each_new_connector_in_state(state, conn, conn_state, i) {
     106         [ #  # ]:          0 :                 if (!conn_state->self_refresh_aware)
     107                 :          0 :                         goto out;
     108                 :            :         }
     109                 :            : 
     110                 :          0 :         crtc_state->active = false;
     111                 :          0 :         crtc_state->self_refresh_active = true;
     112                 :            : 
     113                 :          0 :         ret = drm_atomic_commit(state);
     114         [ #  # ]:          0 :         if (ret)
     115                 :          0 :                 goto out;
     116                 :            : 
     117                 :          0 : out:
     118         [ #  # ]:          0 :         if (ret == -EDEADLK) {
     119                 :          0 :                 drm_atomic_state_clear(state);
     120                 :          0 :                 ret = drm_modeset_backoff(&ctx);
     121         [ #  # ]:          0 :                 if (!ret)
     122                 :          0 :                         goto retry;
     123                 :            :         }
     124                 :            : 
     125                 :          0 :         drm_atomic_state_put(state);
     126                 :            : 
     127                 :          0 : out_drop_locks:
     128                 :          0 :         drm_modeset_drop_locks(&ctx);
     129                 :          0 :         drm_modeset_acquire_fini(&ctx);
     130                 :          0 : }
     131                 :            : 
     132                 :            : /**
     133                 :            :  * drm_self_refresh_helper_update_avg_times - Updates a crtc's SR time averages
     134                 :            :  * @state: the state which has just been applied to hardware
     135                 :            :  * @commit_time_ms: the amount of time in ms that this commit took to complete
     136                 :            :  * @new_self_refresh_mask: bitmask of crtc's that have self_refresh_active in
     137                 :            :  *    new state
     138                 :            :  *
     139                 :            :  * Called after &drm_mode_config_funcs.atomic_commit_tail, this function will
     140                 :            :  * update the average entry/exit self refresh times on self refresh transitions.
     141                 :            :  * These averages will be used when calculating how long to delay before
     142                 :            :  * entering self refresh mode after activity.
     143                 :            :  */
     144                 :            : void
     145                 :          0 : drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state,
     146                 :            :                                          unsigned int commit_time_ms,
     147                 :            :                                          unsigned int new_self_refresh_mask)
     148                 :            : {
     149                 :          0 :         struct drm_crtc *crtc;
     150                 :          0 :         struct drm_crtc_state *old_crtc_state;
     151                 :          0 :         int i;
     152                 :            : 
     153   [ #  #  #  # ]:          0 :         for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
     154                 :          0 :                 bool new_self_refresh_active = new_self_refresh_mask & BIT(i);
     155                 :          0 :                 struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
     156                 :          0 :                 struct ewma_psr_time *time;
     157                 :            : 
     158         [ #  # ]:          0 :                 if (old_crtc_state->self_refresh_active ==
     159                 :            :                     new_self_refresh_active)
     160                 :          0 :                         continue;
     161                 :            : 
     162         [ #  # ]:          0 :                 if (new_self_refresh_active)
     163                 :          0 :                         time = &sr_data->entry_avg_ms;
     164                 :            :                 else
     165                 :          0 :                         time = &sr_data->exit_avg_ms;
     166                 :            : 
     167                 :          0 :                 mutex_lock(&sr_data->avg_mutex);
     168         [ #  # ]:          0 :                 ewma_psr_time_add(time, commit_time_ms);
     169                 :          0 :                 mutex_unlock(&sr_data->avg_mutex);
     170                 :            :         }
     171                 :          0 : }
     172                 :            : EXPORT_SYMBOL(drm_self_refresh_helper_update_avg_times);
     173                 :            : 
     174                 :            : /**
     175                 :            :  * drm_self_refresh_helper_alter_state - Alters the atomic state for SR exit
     176                 :            :  * @state: the state currently being checked
     177                 :            :  *
     178                 :            :  * Called at the end of atomic check. This function checks the state for flags
     179                 :            :  * incompatible with self refresh exit and changes them. This is a bit
     180                 :            :  * disingenuous since userspace is expecting one thing and we're giving it
     181                 :            :  * another. However in order to keep self refresh entirely hidden from
     182                 :            :  * userspace, this is required.
     183                 :            :  *
     184                 :            :  * At the end, we queue up the self refresh entry work so we can enter PSR after
     185                 :            :  * the desired delay.
     186                 :            :  */
     187                 :          0 : void drm_self_refresh_helper_alter_state(struct drm_atomic_state *state)
     188                 :            : {
     189                 :          0 :         struct drm_crtc *crtc;
     190                 :          0 :         struct drm_crtc_state *crtc_state;
     191                 :          0 :         int i;
     192                 :            : 
     193   [ #  #  #  # ]:          0 :         if (state->async_update || !state->allow_modeset) {
     194   [ #  #  #  # ]:          0 :                 for_each_old_crtc_in_state(state, crtc, crtc_state, i) {
     195         [ #  # ]:          0 :                         if (crtc_state->self_refresh_active) {
     196                 :          0 :                                 state->async_update = false;
     197                 :          0 :                                 state->allow_modeset = true;
     198                 :          0 :                                 break;
     199                 :            :                         }
     200                 :            :                 }
     201                 :            :         }
     202                 :            : 
     203   [ #  #  #  # ]:          0 :         for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
     204                 :          0 :                 struct drm_self_refresh_data *sr_data;
     205                 :          0 :                 unsigned int delay;
     206                 :            : 
     207                 :            :                 /* Don't trigger the entry timer when we're already in SR */
     208         [ #  # ]:          0 :                 if (crtc_state->self_refresh_active)
     209                 :          0 :                         continue;
     210                 :            : 
     211                 :          0 :                 sr_data = crtc->self_refresh_data;
     212         [ #  # ]:          0 :                 if (!sr_data)
     213                 :          0 :                         continue;
     214                 :            : 
     215                 :          0 :                 mutex_lock(&sr_data->avg_mutex);
     216                 :          0 :                 delay = (ewma_psr_time_read(&sr_data->entry_avg_ms) +
     217                 :          0 :                          ewma_psr_time_read(&sr_data->exit_avg_ms)) * 2;
     218                 :          0 :                 mutex_unlock(&sr_data->avg_mutex);
     219                 :            : 
     220         [ #  # ]:          0 :                 mod_delayed_work(system_wq, &sr_data->entry_work,
     221                 :            :                                  msecs_to_jiffies(delay));
     222                 :            :         }
     223                 :          0 : }
     224                 :            : EXPORT_SYMBOL(drm_self_refresh_helper_alter_state);
     225                 :            : 
     226                 :            : /**
     227                 :            :  * drm_self_refresh_helper_init - Initializes self refresh helpers for a crtc
     228                 :            :  * @crtc: the crtc which supports self refresh supported displays
     229                 :            :  *
     230                 :            :  * Returns zero if successful or -errno on failure
     231                 :            :  */
     232                 :          0 : int drm_self_refresh_helper_init(struct drm_crtc *crtc)
     233                 :            : {
     234                 :          0 :         struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
     235                 :            : 
     236                 :            :         /* Helper is already initialized */
     237   [ #  #  #  # ]:          0 :         if (WARN_ON(sr_data))
     238                 :            :                 return -EINVAL;
     239                 :            : 
     240                 :          0 :         sr_data = kzalloc(sizeof(*sr_data), GFP_KERNEL);
     241         [ #  # ]:          0 :         if (!sr_data)
     242                 :            :                 return -ENOMEM;
     243                 :            : 
     244                 :          0 :         INIT_DELAYED_WORK(&sr_data->entry_work,
     245                 :            :                           drm_self_refresh_helper_entry_work);
     246                 :          0 :         sr_data->crtc = crtc;
     247                 :          0 :         mutex_init(&sr_data->avg_mutex);
     248                 :          0 :         ewma_psr_time_init(&sr_data->entry_avg_ms);
     249                 :          0 :         ewma_psr_time_init(&sr_data->exit_avg_ms);
     250                 :            : 
     251                 :            :         /*
     252                 :            :          * Seed the averages so they're non-zero (and sufficiently large
     253                 :            :          * for even poorly performing panels). As time goes on, this will be
     254                 :            :          * averaged out and the values will trend to their true value.
     255                 :            :          */
     256         [ #  # ]:          0 :         ewma_psr_time_add(&sr_data->entry_avg_ms, SELF_REFRESH_AVG_SEED_MS);
     257         [ #  # ]:          0 :         ewma_psr_time_add(&sr_data->exit_avg_ms, SELF_REFRESH_AVG_SEED_MS);
     258                 :            : 
     259                 :          0 :         crtc->self_refresh_data = sr_data;
     260                 :          0 :         return 0;
     261                 :            : }
     262                 :            : EXPORT_SYMBOL(drm_self_refresh_helper_init);
     263                 :            : 
     264                 :            : /**
     265                 :            :  * drm_self_refresh_helper_cleanup - Cleans up self refresh helpers for a crtc
     266                 :            :  * @crtc: the crtc to cleanup
     267                 :            :  */
     268                 :          0 : void drm_self_refresh_helper_cleanup(struct drm_crtc *crtc)
     269                 :            : {
     270                 :          0 :         struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
     271                 :            : 
     272                 :            :         /* Helper is already uninitialized */
     273         [ #  # ]:          0 :         if (!sr_data)
     274                 :            :                 return;
     275                 :            : 
     276                 :          0 :         crtc->self_refresh_data = NULL;
     277                 :            : 
     278                 :          0 :         cancel_delayed_work_sync(&sr_data->entry_work);
     279                 :          0 :         kfree(sr_data);
     280                 :            : }
     281                 :            : EXPORT_SYMBOL(drm_self_refresh_helper_cleanup);