Line data    Source code

       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             :         struct drm_modeset_acquire_ctx ctx;
      75             :         struct drm_atomic_state *state;
      76             :         struct drm_connector *conn;
      77             :         struct drm_connector_state *conn_state;
      78             :         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             :                 ret = -ENOMEM;
      86             :                 goto out_drop_locks;
      87             :         }
      88             : 
      89             : 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             :                 goto out;
     100             : 
     101           0 :         ret = drm_atomic_add_affected_connectors(state, crtc);
     102           0 :         if (ret)
     103             :                 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             :                         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             :         if (ret)
     115             :                 goto out;
     116             : 
     117             : 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             :                         goto retry;
     123             :         }
     124             : 
     125             :         drm_atomic_state_put(state);
     126             : 
     127             : 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             :         struct drm_crtc *crtc;
     150             :         struct drm_crtc_state *old_crtc_state;
     151             :         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             :                 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             :         struct drm_crtc *crtc;
     190             :         struct drm_crtc_state *crtc_state;
     191             :         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             :                 struct drm_self_refresh_data *sr_data;
     205             :                 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);