GNU Linux-libre 5.10.219-gnu1
[releases.git] / drivers / gpu / drm / drm_self_refresh_helper.c
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 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 static void drm_self_refresh_helper_entry_work(struct work_struct *work)
68 {
69         struct drm_self_refresh_data *sr_data = container_of(
70                                 to_delayed_work(work),
71                                 struct drm_self_refresh_data, entry_work);
72         struct drm_crtc *crtc = sr_data->crtc;
73         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         int i, ret = 0;
80
81         drm_modeset_acquire_init(&ctx, 0);
82
83         state = drm_atomic_state_alloc(dev);
84         if (!state) {
85                 ret = -ENOMEM;
86                 goto out_drop_locks;
87         }
88
89 retry:
90         state->acquire_ctx = &ctx;
91
92         crtc_state = drm_atomic_get_crtc_state(state, crtc);
93         if (IS_ERR(crtc_state)) {
94                 ret = PTR_ERR(crtc_state);
95                 goto out;
96         }
97
98         if (!crtc_state->enable)
99                 goto out;
100
101         ret = drm_atomic_add_affected_connectors(state, crtc);
102         if (ret)
103                 goto out;
104
105         for_each_new_connector_in_state(state, conn, conn_state, i) {
106                 if (!conn_state->self_refresh_aware)
107                         goto out;
108         }
109
110         crtc_state->active = false;
111         crtc_state->self_refresh_active = true;
112
113         ret = drm_atomic_commit(state);
114         if (ret)
115                 goto out;
116
117 out:
118         if (ret == -EDEADLK) {
119                 drm_atomic_state_clear(state);
120                 ret = drm_modeset_backoff(&ctx);
121                 if (!ret)
122                         goto retry;
123         }
124
125         drm_atomic_state_put(state);
126
127 out_drop_locks:
128         drm_modeset_drop_locks(&ctx);
129         drm_modeset_acquire_fini(&ctx);
130 }
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 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         for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
154                 bool new_self_refresh_active = new_self_refresh_mask & BIT(i);
155                 struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
156                 struct ewma_psr_time *time;
157
158                 if (old_crtc_state->self_refresh_active ==
159                     new_self_refresh_active)
160                         continue;
161
162                 if (new_self_refresh_active)
163                         time = &sr_data->entry_avg_ms;
164                 else
165                         time = &sr_data->exit_avg_ms;
166
167                 mutex_lock(&sr_data->avg_mutex);
168                 ewma_psr_time_add(time, commit_time_ms);
169                 mutex_unlock(&sr_data->avg_mutex);
170         }
171 }
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 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         if (state->async_update || !state->allow_modeset) {
194                 for_each_old_crtc_in_state(state, crtc, crtc_state, i) {
195                         if (crtc_state->self_refresh_active) {
196                                 state->async_update = false;
197                                 state->allow_modeset = true;
198                                 break;
199                         }
200                 }
201         }
202
203         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                 if (crtc_state->self_refresh_active)
209                         continue;
210
211                 sr_data = crtc->self_refresh_data;
212                 if (!sr_data)
213                         continue;
214
215                 mutex_lock(&sr_data->avg_mutex);
216                 delay = (ewma_psr_time_read(&sr_data->entry_avg_ms) +
217                          ewma_psr_time_read(&sr_data->exit_avg_ms)) * 2;
218                 mutex_unlock(&sr_data->avg_mutex);
219
220                 mod_delayed_work(system_wq, &sr_data->entry_work,
221                                  msecs_to_jiffies(delay));
222         }
223 }
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 int drm_self_refresh_helper_init(struct drm_crtc *crtc)
233 {
234         struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
235
236         /* Helper is already initialized */
237         if (WARN_ON(sr_data))
238                 return -EINVAL;
239
240         sr_data = kzalloc(sizeof(*sr_data), GFP_KERNEL);
241         if (!sr_data)
242                 return -ENOMEM;
243
244         INIT_DELAYED_WORK(&sr_data->entry_work,
245                           drm_self_refresh_helper_entry_work);
246         sr_data->crtc = crtc;
247         mutex_init(&sr_data->avg_mutex);
248         ewma_psr_time_init(&sr_data->entry_avg_ms);
249         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         ewma_psr_time_add(&sr_data->entry_avg_ms, SELF_REFRESH_AVG_SEED_MS);
257         ewma_psr_time_add(&sr_data->exit_avg_ms, SELF_REFRESH_AVG_SEED_MS);
258
259         crtc->self_refresh_data = sr_data;
260         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 void drm_self_refresh_helper_cleanup(struct drm_crtc *crtc)
269 {
270         struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
271
272         /* Helper is already uninitialized */
273         if (!sr_data)
274                 return;
275
276         crtc->self_refresh_data = NULL;
277
278         cancel_delayed_work_sync(&sr_data->entry_work);
279         kfree(sr_data);
280 }
281 EXPORT_SYMBOL(drm_self_refresh_helper_cleanup);