1 /*
2  * Copyright © 2015 Intel Corporation
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  */
23 
24 #include <linux/kernel.h>
25 
26 #include "i915_drv.h"
27 #include "intel_display_types.h"
28 #include "intel_hotplug.h"
29 
30 /**
31  * DOC: Hotplug
32  *
33  * Simply put, hotplug occurs when a display is connected to or disconnected
34  * from the system. However, there may be adapters and docking stations and
35  * Display Port short pulses and MST devices involved, complicating matters.
36  *
37  * Hotplug in i915 is handled in many different levels of abstraction.
38  *
39  * The platform dependent interrupt handling code in i915_irq.c enables,
40  * disables, and does preliminary handling of the interrupts. The interrupt
41  * handlers gather the hotplug detect (HPD) information from relevant registers
42  * into a platform independent mask of hotplug pins that have fired.
43  *
44  * The platform independent interrupt handler intel_hpd_irq_handler() in
45  * intel_hotplug.c does hotplug irq storm detection and mitigation, and passes
46  * further processing to appropriate bottom halves (Display Port specific and
47  * regular hotplug).
48  *
49  * The Display Port work function i915_digport_work_func() calls into
50  * intel_dp_hpd_pulse() via hooks, which handles DP short pulses and DP MST long
51  * pulses, with failures and non-MST long pulses triggering regular hotplug
52  * processing on the connector.
53  *
54  * The regular hotplug work function i915_hotplug_work_func() calls connector
55  * detect hooks, and, if connector status changes, triggers sending of hotplug
56  * uevent to userspace via drm_kms_helper_hotplug_event().
57  *
58  * Finally, the userspace is responsible for triggering a modeset upon receiving
59  * the hotplug uevent, disabling or enabling the crtc as needed.
60  *
61  * The hotplug interrupt storm detection and mitigation code keeps track of the
62  * number of interrupts per hotplug pin per a period of time, and if the number
63  * of interrupts exceeds a certain threshold, the interrupt is disabled for a
64  * while before being re-enabled. The intention is to mitigate issues raising
65  * from broken hardware triggering massive amounts of interrupts and grinding
66  * the system to a halt.
67  *
68  * Current implementation expects that hotplug interrupt storm will not be
69  * seen when display port sink is connected, hence on platforms whose DP
70  * callback is handled by i915_digport_work_func reenabling of hpd is not
71  * performed (it was never expected to be disabled in the first place ;) )
72  * this is specific to DP sinks handled by this routine and any other display
73  * such as HDMI or DVI enabled on the same port will have proper logic since
74  * it will use i915_hotplug_work_func where this logic is handled.
75  */
76 
77 /**
78  * intel_hpd_pin_default - return default pin associated with certain port.
79  * @dev_priv: private driver data pointer
80  * @port: the hpd port to get associated pin
81  *
82  * It is only valid and used by digital port encoder.
83  *
84  * Return pin that is associatade with @port.
85  */
86 enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
87 				   enum port port)
88 {
89 	return HPD_PORT_A + port - PORT_A;
90 }
91 
92 #define HPD_STORM_DETECT_PERIOD		1000
93 #define HPD_STORM_REENABLE_DELAY	(2 * 60 * 1000)
94 #define HPD_RETRY_DELAY			1000
95 
96 static enum hpd_pin
97 intel_connector_hpd_pin(struct intel_connector *connector)
98 {
99 	struct intel_encoder *encoder = intel_attached_encoder(connector);
100 
101 	/*
102 	 * MST connectors get their encoder attached dynamically
103 	 * so need to make sure we have an encoder here. But since
104 	 * MST encoders have their hpd_pin set to HPD_NONE we don't
105 	 * have to special case them beyond that.
106 	 */
107 	return encoder ? encoder->hpd_pin : HPD_NONE;
108 }
109 
110 /**
111  * intel_hpd_irq_storm_detect - gather stats and detect HPD IRQ storm on a pin
112  * @dev_priv: private driver data pointer
113  * @pin: the pin to gather stats on
114  * @long_hpd: whether the HPD IRQ was long or short
115  *
116  * Gather stats about HPD IRQs from the specified @pin, and detect IRQ
117  * storms. Only the pin specific stats and state are changed, the caller is
118  * responsible for further action.
119  *
120  * The number of IRQs that are allowed within @HPD_STORM_DETECT_PERIOD is
121  * stored in @dev_priv->hotplug.hpd_storm_threshold which defaults to
122  * @HPD_STORM_DEFAULT_THRESHOLD. Long IRQs count as +10 to this threshold, and
123  * short IRQs count as +1. If this threshold is exceeded, it's considered an
124  * IRQ storm and the IRQ state is set to @HPD_MARK_DISABLED.
125  *
126  * By default, most systems will only count long IRQs towards
127  * &dev_priv->hotplug.hpd_storm_threshold. However, some older systems also
128  * suffer from short IRQ storms and must also track these. Because short IRQ
129  * storms are naturally caused by sideband interactions with DP MST devices,
130  * short IRQ detection is only enabled for systems without DP MST support.
131  * Systems which are new enough to support DP MST are far less likely to
132  * suffer from IRQ storms at all, so this is fine.
133  *
134  * The HPD threshold can be controlled through i915_hpd_storm_ctl in debugfs,
135  * and should only be adjusted for automated hotplug testing.
136  *
137  * Return true if an IRQ storm was detected on @pin.
138  */
139 static bool intel_hpd_irq_storm_detect(struct drm_i915_private *dev_priv,
140 				       enum hpd_pin pin, bool long_hpd)
141 {
142 	struct i915_hotplug *hpd = &dev_priv->hotplug;
143 	unsigned long start = hpd->stats[pin].last_jiffies;
144 	unsigned long end = start + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD);
145 	const int increment = long_hpd ? 10 : 1;
146 	const int threshold = hpd->hpd_storm_threshold;
147 	bool storm = false;
148 
149 	if (!threshold ||
150 	    (!long_hpd && !dev_priv->hotplug.hpd_short_storm_enabled))
151 		return false;
152 
153 	if (!time_in_range(jiffies, start, end)) {
154 		hpd->stats[pin].last_jiffies = jiffies;
155 		hpd->stats[pin].count = 0;
156 	}
157 
158 	hpd->stats[pin].count += increment;
159 	if (hpd->stats[pin].count > threshold) {
160 		hpd->stats[pin].state = HPD_MARK_DISABLED;
161 		drm_dbg_kms(&dev_priv->drm,
162 			    "HPD interrupt storm detected on PIN %d\n", pin);
163 		storm = true;
164 	} else {
165 		drm_dbg_kms(&dev_priv->drm,
166 			    "Received HPD interrupt on PIN %d - cnt: %d\n",
167 			      pin,
168 			      hpd->stats[pin].count);
169 	}
170 
171 	return storm;
172 }
173 
174 static void
175 intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private *dev_priv)
176 {
177 	struct drm_device *dev = &dev_priv->drm;
178 	struct drm_connector_list_iter conn_iter;
179 	struct intel_connector *connector;
180 	bool hpd_disabled = false;
181 
182 	lockdep_assert_held(&dev_priv->irq_lock);
183 
184 	drm_connector_list_iter_begin(dev, &conn_iter);
185 	for_each_intel_connector_iter(connector, &conn_iter) {
186 		enum hpd_pin pin;
187 
188 		if (connector->base.polled != DRM_CONNECTOR_POLL_HPD)
189 			continue;
190 
191 		pin = intel_connector_hpd_pin(connector);
192 		if (pin == HPD_NONE ||
193 		    dev_priv->hotplug.stats[pin].state != HPD_MARK_DISABLED)
194 			continue;
195 
196 		drm_info(&dev_priv->drm,
197 			 "HPD interrupt storm detected on connector %s: "
198 			 "switching from hotplug detection to polling\n",
199 			 connector->base.name);
200 
201 		dev_priv->hotplug.stats[pin].state = HPD_DISABLED;
202 		connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
203 			DRM_CONNECTOR_POLL_DISCONNECT;
204 		hpd_disabled = true;
205 	}
206 	drm_connector_list_iter_end(&conn_iter);
207 
208 	/* Enable polling and queue hotplug re-enabling. */
209 	if (hpd_disabled) {
210 		drm_kms_helper_poll_enable(dev);
211 		mod_delayed_work(system_wq, &dev_priv->hotplug.reenable_work,
212 				 msecs_to_jiffies(HPD_STORM_REENABLE_DELAY));
213 	}
214 }
215 
216 static void intel_hpd_irq_setup(struct drm_i915_private *i915)
217 {
218 	if (i915->display_irqs_enabled && i915->display.hpd_irq_setup)
219 		i915->display.hpd_irq_setup(i915);
220 }
221 
222 static void intel_hpd_irq_storm_reenable_work(struct work_struct *work)
223 {
224 	struct drm_i915_private *dev_priv =
225 		container_of(work, typeof(*dev_priv),
226 			     hotplug.reenable_work.work);
227 	struct drm_device *dev = &dev_priv->drm;
228 	struct drm_connector_list_iter conn_iter;
229 	struct intel_connector *connector;
230 	intel_wakeref_t wakeref;
231 	enum hpd_pin pin;
232 
233 	wakeref = intel_runtime_pm_get(&dev_priv->runtime_pm);
234 
235 	spin_lock_irq(&dev_priv->irq_lock);
236 
237 	drm_connector_list_iter_begin(dev, &conn_iter);
238 	for_each_intel_connector_iter(connector, &conn_iter) {
239 		pin = intel_connector_hpd_pin(connector);
240 		if (pin == HPD_NONE ||
241 		    dev_priv->hotplug.stats[pin].state != HPD_DISABLED)
242 			continue;
243 
244 		if (connector->base.polled != connector->polled)
245 			drm_dbg(&dev_priv->drm,
246 				"Reenabling HPD on connector %s\n",
247 				connector->base.name);
248 		connector->base.polled = connector->polled;
249 	}
250 	drm_connector_list_iter_end(&conn_iter);
251 
252 	for_each_hpd_pin(pin) {
253 		if (dev_priv->hotplug.stats[pin].state == HPD_DISABLED)
254 			dev_priv->hotplug.stats[pin].state = HPD_ENABLED;
255 	}
256 
257 	intel_hpd_irq_setup(dev_priv);
258 
259 	spin_unlock_irq(&dev_priv->irq_lock);
260 
261 	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
262 }
263 
264 enum intel_hotplug_state
265 intel_encoder_hotplug(struct intel_encoder *encoder,
266 		      struct intel_connector *connector)
267 {
268 	struct drm_device *dev = connector->base.dev;
269 	enum drm_connector_status old_status;
270 	u64 old_epoch_counter;
271 	bool ret = false;
272 
273 	drm_WARN_ON(dev, !mutex_is_locked(&dev->mode_config.mutex));
274 	old_status = connector->base.status;
275 	old_epoch_counter = connector->base.epoch_counter;
276 
277 	connector->base.status =
278 		drm_helper_probe_detect(&connector->base, NULL, false);
279 
280 	if (old_epoch_counter != connector->base.epoch_counter)
281 		ret = true;
282 
283 	if (ret) {
284 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s (epoch counter %llu->%llu)\n",
285 			      connector->base.base.id,
286 			      connector->base.name,
287 			      drm_get_connector_status_name(old_status),
288 			      drm_get_connector_status_name(connector->base.status),
289 			      old_epoch_counter,
290 			      connector->base.epoch_counter);
291 		return INTEL_HOTPLUG_CHANGED;
292 	}
293 	return INTEL_HOTPLUG_UNCHANGED;
294 }
295 
296 static bool intel_encoder_has_hpd_pulse(struct intel_encoder *encoder)
297 {
298 	return intel_encoder_is_dig_port(encoder) &&
299 		enc_to_dig_port(encoder)->hpd_pulse != NULL;
300 }
301 
302 static void i915_digport_work_func(struct work_struct *work)
303 {
304 	struct drm_i915_private *dev_priv =
305 		container_of(work, struct drm_i915_private, hotplug.dig_port_work);
306 	u32 long_port_mask, short_port_mask;
307 	struct intel_encoder *encoder;
308 	u32 old_bits = 0;
309 
310 	spin_lock_irq(&dev_priv->irq_lock);
311 	long_port_mask = dev_priv->hotplug.long_port_mask;
312 	dev_priv->hotplug.long_port_mask = 0;
313 	short_port_mask = dev_priv->hotplug.short_port_mask;
314 	dev_priv->hotplug.short_port_mask = 0;
315 	spin_unlock_irq(&dev_priv->irq_lock);
316 
317 	for_each_intel_encoder(&dev_priv->drm, encoder) {
318 		struct intel_digital_port *dig_port;
319 		enum port port = encoder->port;
320 		bool long_hpd, short_hpd;
321 		enum irqreturn ret;
322 
323 		if (!intel_encoder_has_hpd_pulse(encoder))
324 			continue;
325 
326 		long_hpd = long_port_mask & BIT(port);
327 		short_hpd = short_port_mask & BIT(port);
328 
329 		if (!long_hpd && !short_hpd)
330 			continue;
331 
332 		dig_port = enc_to_dig_port(encoder);
333 
334 		ret = dig_port->hpd_pulse(dig_port, long_hpd);
335 		if (ret == IRQ_NONE) {
336 			/* fall back to old school hpd */
337 			old_bits |= BIT(encoder->hpd_pin);
338 		}
339 	}
340 
341 	if (old_bits) {
342 		spin_lock_irq(&dev_priv->irq_lock);
343 		dev_priv->hotplug.event_bits |= old_bits;
344 		spin_unlock_irq(&dev_priv->irq_lock);
345 		queue_delayed_work(system_wq, &dev_priv->hotplug.hotplug_work, 0);
346 	}
347 }
348 
349 /**
350  * intel_hpd_trigger_irq - trigger an hpd irq event for a port
351  * @dig_port: digital port
352  *
353  * Trigger an HPD interrupt event for the given port, emulating a short pulse
354  * generated by the sink, and schedule the dig port work to handle it.
355  */
356 void intel_hpd_trigger_irq(struct intel_digital_port *dig_port)
357 {
358 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
359 
360 	spin_lock_irq(&i915->irq_lock);
361 	i915->hotplug.short_port_mask |= BIT(dig_port->base.port);
362 	spin_unlock_irq(&i915->irq_lock);
363 
364 	queue_work(i915->hotplug.dp_wq, &i915->hotplug.dig_port_work);
365 }
366 
367 /*
368  * Handle hotplug events outside the interrupt handler proper.
369  */
370 static void i915_hotplug_work_func(struct work_struct *work)
371 {
372 	struct drm_i915_private *dev_priv =
373 		container_of(work, struct drm_i915_private,
374 			     hotplug.hotplug_work.work);
375 	struct drm_device *dev = &dev_priv->drm;
376 	struct drm_connector_list_iter conn_iter;
377 	struct intel_connector *connector;
378 	u32 changed = 0, retry = 0;
379 	u32 hpd_event_bits;
380 	u32 hpd_retry_bits;
381 
382 	mutex_lock(&dev->mode_config.mutex);
383 	drm_dbg_kms(&dev_priv->drm, "running encoder hotplug functions\n");
384 
385 	spin_lock_irq(&dev_priv->irq_lock);
386 
387 	hpd_event_bits = dev_priv->hotplug.event_bits;
388 	dev_priv->hotplug.event_bits = 0;
389 	hpd_retry_bits = dev_priv->hotplug.retry_bits;
390 	dev_priv->hotplug.retry_bits = 0;
391 
392 	/* Enable polling for connectors which had HPD IRQ storms */
393 	intel_hpd_irq_storm_switch_to_polling(dev_priv);
394 
395 	spin_unlock_irq(&dev_priv->irq_lock);
396 
397 	drm_connector_list_iter_begin(dev, &conn_iter);
398 	for_each_intel_connector_iter(connector, &conn_iter) {
399 		enum hpd_pin pin;
400 		u32 hpd_bit;
401 
402 		pin = intel_connector_hpd_pin(connector);
403 		if (pin == HPD_NONE)
404 			continue;
405 
406 		hpd_bit = BIT(pin);
407 		if ((hpd_event_bits | hpd_retry_bits) & hpd_bit) {
408 			struct intel_encoder *encoder =
409 				intel_attached_encoder(connector);
410 
411 			if (hpd_event_bits & hpd_bit)
412 				connector->hotplug_retries = 0;
413 			else
414 				connector->hotplug_retries++;
415 
416 			drm_dbg_kms(&dev_priv->drm,
417 				    "Connector %s (pin %i) received hotplug event. (retry %d)\n",
418 				    connector->base.name, pin,
419 				    connector->hotplug_retries);
420 
421 			switch (encoder->hotplug(encoder, connector)) {
422 			case INTEL_HOTPLUG_UNCHANGED:
423 				break;
424 			case INTEL_HOTPLUG_CHANGED:
425 				changed |= hpd_bit;
426 				break;
427 			case INTEL_HOTPLUG_RETRY:
428 				retry |= hpd_bit;
429 				break;
430 			}
431 		}
432 	}
433 	drm_connector_list_iter_end(&conn_iter);
434 	mutex_unlock(&dev->mode_config.mutex);
435 
436 	if (changed)
437 		drm_kms_helper_hotplug_event(dev);
438 
439 	/* Remove shared HPD pins that have changed */
440 	retry &= ~changed;
441 	if (retry) {
442 		spin_lock_irq(&dev_priv->irq_lock);
443 		dev_priv->hotplug.retry_bits |= retry;
444 		spin_unlock_irq(&dev_priv->irq_lock);
445 
446 		mod_delayed_work(system_wq, &dev_priv->hotplug.hotplug_work,
447 				 msecs_to_jiffies(HPD_RETRY_DELAY));
448 	}
449 }
450 
451 
452 /**
453  * intel_hpd_irq_handler - main hotplug irq handler
454  * @dev_priv: drm_i915_private
455  * @pin_mask: a mask of hpd pins that have triggered the irq
456  * @long_mask: a mask of hpd pins that may be long hpd pulses
457  *
458  * This is the main hotplug irq handler for all platforms. The platform specific
459  * irq handlers call the platform specific hotplug irq handlers, which read and
460  * decode the appropriate registers into bitmasks about hpd pins that have
461  * triggered (@pin_mask), and which of those pins may be long pulses
462  * (@long_mask). The @long_mask is ignored if the port corresponding to the pin
463  * is not a digital port.
464  *
465  * Here, we do hotplug irq storm detection and mitigation, and pass further
466  * processing to appropriate bottom halves.
467  */
468 void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
469 			   u32 pin_mask, u32 long_mask)
470 {
471 	struct intel_encoder *encoder;
472 	bool storm_detected = false;
473 	bool queue_dig = false, queue_hp = false;
474 	u32 long_hpd_pulse_mask = 0;
475 	u32 short_hpd_pulse_mask = 0;
476 	enum hpd_pin pin;
477 
478 	if (!pin_mask)
479 		return;
480 
481 	spin_lock(&dev_priv->irq_lock);
482 
483 	/*
484 	 * Determine whether ->hpd_pulse() exists for each pin, and
485 	 * whether we have a short or a long pulse. This is needed
486 	 * as each pin may have up to two encoders (HDMI and DP) and
487 	 * only the one of them (DP) will have ->hpd_pulse().
488 	 */
489 	for_each_intel_encoder(&dev_priv->drm, encoder) {
490 		enum port port = encoder->port;
491 		bool long_hpd;
492 
493 		pin = encoder->hpd_pin;
494 		if (!(BIT(pin) & pin_mask))
495 			continue;
496 
497 		if (!intel_encoder_has_hpd_pulse(encoder))
498 			continue;
499 
500 		long_hpd = long_mask & BIT(pin);
501 
502 		drm_dbg(&dev_priv->drm,
503 			"digital hpd on [ENCODER:%d:%s] - %s\n",
504 			encoder->base.base.id, encoder->base.name,
505 			long_hpd ? "long" : "short");
506 		queue_dig = true;
507 
508 		if (long_hpd) {
509 			long_hpd_pulse_mask |= BIT(pin);
510 			dev_priv->hotplug.long_port_mask |= BIT(port);
511 		} else {
512 			short_hpd_pulse_mask |= BIT(pin);
513 			dev_priv->hotplug.short_port_mask |= BIT(port);
514 		}
515 	}
516 
517 	/* Now process each pin just once */
518 	for_each_hpd_pin(pin) {
519 		bool long_hpd;
520 
521 		if (!(BIT(pin) & pin_mask))
522 			continue;
523 
524 		if (dev_priv->hotplug.stats[pin].state == HPD_DISABLED) {
525 			/*
526 			 * On GMCH platforms the interrupt mask bits only
527 			 * prevent irq generation, not the setting of the
528 			 * hotplug bits itself. So only WARN about unexpected
529 			 * interrupts on saner platforms.
530 			 */
531 			drm_WARN_ONCE(&dev_priv->drm, !HAS_GMCH(dev_priv),
532 				      "Received HPD interrupt on pin %d although disabled\n",
533 				      pin);
534 			continue;
535 		}
536 
537 		if (dev_priv->hotplug.stats[pin].state != HPD_ENABLED)
538 			continue;
539 
540 		/*
541 		 * Delegate to ->hpd_pulse() if one of the encoders for this
542 		 * pin has it, otherwise let the hotplug_work deal with this
543 		 * pin directly.
544 		 */
545 		if (((short_hpd_pulse_mask | long_hpd_pulse_mask) & BIT(pin))) {
546 			long_hpd = long_hpd_pulse_mask & BIT(pin);
547 		} else {
548 			dev_priv->hotplug.event_bits |= BIT(pin);
549 			long_hpd = true;
550 			queue_hp = true;
551 		}
552 
553 		if (intel_hpd_irq_storm_detect(dev_priv, pin, long_hpd)) {
554 			dev_priv->hotplug.event_bits &= ~BIT(pin);
555 			storm_detected = true;
556 			queue_hp = true;
557 		}
558 	}
559 
560 	/*
561 	 * Disable any IRQs that storms were detected on. Polling enablement
562 	 * happens later in our hotplug work.
563 	 */
564 	if (storm_detected)
565 		intel_hpd_irq_setup(dev_priv);
566 	spin_unlock(&dev_priv->irq_lock);
567 
568 	/*
569 	 * Our hotplug handler can grab modeset locks (by calling down into the
570 	 * fb helpers). Hence it must not be run on our own dev-priv->wq work
571 	 * queue for otherwise the flush_work in the pageflip code will
572 	 * deadlock.
573 	 */
574 	if (queue_dig)
575 		queue_work(dev_priv->hotplug.dp_wq, &dev_priv->hotplug.dig_port_work);
576 	if (queue_hp)
577 		queue_delayed_work(system_wq, &dev_priv->hotplug.hotplug_work, 0);
578 }
579 
580 /**
581  * intel_hpd_init - initializes and enables hpd support
582  * @dev_priv: i915 device instance
583  *
584  * This function enables the hotplug support. It requires that interrupts have
585  * already been enabled with intel_irq_init_hw(). From this point on hotplug and
586  * poll request can run concurrently to other code, so locking rules must be
587  * obeyed.
588  *
589  * This is a separate step from interrupt enabling to simplify the locking rules
590  * in the driver load and resume code.
591  *
592  * Also see: intel_hpd_poll_enable() and intel_hpd_poll_disable().
593  */
594 void intel_hpd_init(struct drm_i915_private *dev_priv)
595 {
596 	int i;
597 
598 	if (!HAS_DISPLAY(dev_priv))
599 		return;
600 
601 	for_each_hpd_pin(i) {
602 		dev_priv->hotplug.stats[i].count = 0;
603 		dev_priv->hotplug.stats[i].state = HPD_ENABLED;
604 	}
605 
606 	/*
607 	 * Interrupt setup is already guaranteed to be single-threaded, this is
608 	 * just to make the assert_spin_locked checks happy.
609 	 */
610 	spin_lock_irq(&dev_priv->irq_lock);
611 	intel_hpd_irq_setup(dev_priv);
612 	spin_unlock_irq(&dev_priv->irq_lock);
613 }
614 
615 static void i915_hpd_poll_init_work(struct work_struct *work)
616 {
617 	struct drm_i915_private *dev_priv =
618 		container_of(work, struct drm_i915_private,
619 			     hotplug.poll_init_work);
620 	struct drm_device *dev = &dev_priv->drm;
621 	struct drm_connector_list_iter conn_iter;
622 	struct intel_connector *connector;
623 	bool enabled;
624 
625 	mutex_lock(&dev->mode_config.mutex);
626 
627 	enabled = READ_ONCE(dev_priv->hotplug.poll_enabled);
628 
629 	drm_connector_list_iter_begin(dev, &conn_iter);
630 	for_each_intel_connector_iter(connector, &conn_iter) {
631 		enum hpd_pin pin;
632 
633 		pin = intel_connector_hpd_pin(connector);
634 		if (pin == HPD_NONE)
635 			continue;
636 
637 		connector->base.polled = connector->polled;
638 
639 		if (enabled && connector->base.polled == DRM_CONNECTOR_POLL_HPD)
640 			connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
641 				DRM_CONNECTOR_POLL_DISCONNECT;
642 	}
643 	drm_connector_list_iter_end(&conn_iter);
644 
645 	if (enabled)
646 		drm_kms_helper_poll_enable(dev);
647 
648 	mutex_unlock(&dev->mode_config.mutex);
649 
650 	/*
651 	 * We might have missed any hotplugs that happened while we were
652 	 * in the middle of disabling polling
653 	 */
654 	if (!enabled)
655 		drm_helper_hpd_irq_event(dev);
656 }
657 
658 /**
659  * intel_hpd_poll_enable - enable polling for connectors with hpd
660  * @dev_priv: i915 device instance
661  *
662  * This function enables polling for all connectors which support HPD.
663  * Under certain conditions HPD may not be functional. On most Intel GPUs,
664  * this happens when we enter runtime suspend.
665  * On Valleyview and Cherryview systems, this also happens when we shut off all
666  * of the powerwells.
667  *
668  * Since this function can get called in contexts where we're already holding
669  * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
670  * worker.
671  *
672  * Also see: intel_hpd_init() and intel_hpd_poll_disable().
673  */
674 void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
675 {
676 	if (!HAS_DISPLAY(dev_priv))
677 		return;
678 
679 	WRITE_ONCE(dev_priv->hotplug.poll_enabled, true);
680 
681 	/*
682 	 * We might already be holding dev->mode_config.mutex, so do this in a
683 	 * seperate worker
684 	 * As well, there's no issue if we race here since we always reschedule
685 	 * this worker anyway
686 	 */
687 	schedule_work(&dev_priv->hotplug.poll_init_work);
688 }
689 
690 /**
691  * intel_hpd_poll_disable - disable polling for connectors with hpd
692  * @dev_priv: i915 device instance
693  *
694  * This function disables polling for all connectors which support HPD.
695  * Under certain conditions HPD may not be functional. On most Intel GPUs,
696  * this happens when we enter runtime suspend.
697  * On Valleyview and Cherryview systems, this also happens when we shut off all
698  * of the powerwells.
699  *
700  * Since this function can get called in contexts where we're already holding
701  * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
702  * worker.
703  *
704  * Also used during driver init to initialize connector->polled
705  * appropriately for all connectors.
706  *
707  * Also see: intel_hpd_init() and intel_hpd_poll_enable().
708  */
709 void intel_hpd_poll_disable(struct drm_i915_private *dev_priv)
710 {
711 	if (!HAS_DISPLAY(dev_priv))
712 		return;
713 
714 	WRITE_ONCE(dev_priv->hotplug.poll_enabled, false);
715 	schedule_work(&dev_priv->hotplug.poll_init_work);
716 }
717 
718 void intel_hpd_init_work(struct drm_i915_private *dev_priv)
719 {
720 	INIT_DELAYED_WORK(&dev_priv->hotplug.hotplug_work,
721 			  i915_hotplug_work_func);
722 	INIT_WORK(&dev_priv->hotplug.dig_port_work, i915_digport_work_func);
723 	INIT_WORK(&dev_priv->hotplug.poll_init_work, i915_hpd_poll_init_work);
724 	INIT_DELAYED_WORK(&dev_priv->hotplug.reenable_work,
725 			  intel_hpd_irq_storm_reenable_work);
726 }
727 
728 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
729 {
730 	if (!HAS_DISPLAY(dev_priv))
731 		return;
732 
733 	spin_lock_irq(&dev_priv->irq_lock);
734 
735 	dev_priv->hotplug.long_port_mask = 0;
736 	dev_priv->hotplug.short_port_mask = 0;
737 	dev_priv->hotplug.event_bits = 0;
738 	dev_priv->hotplug.retry_bits = 0;
739 
740 	spin_unlock_irq(&dev_priv->irq_lock);
741 
742 	cancel_work_sync(&dev_priv->hotplug.dig_port_work);
743 	cancel_delayed_work_sync(&dev_priv->hotplug.hotplug_work);
744 	cancel_work_sync(&dev_priv->hotplug.poll_init_work);
745 	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
746 }
747 
748 bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
749 {
750 	bool ret = false;
751 
752 	if (pin == HPD_NONE)
753 		return false;
754 
755 	spin_lock_irq(&dev_priv->irq_lock);
756 	if (dev_priv->hotplug.stats[pin].state == HPD_ENABLED) {
757 		dev_priv->hotplug.stats[pin].state = HPD_DISABLED;
758 		ret = true;
759 	}
760 	spin_unlock_irq(&dev_priv->irq_lock);
761 
762 	return ret;
763 }
764 
765 void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
766 {
767 	if (pin == HPD_NONE)
768 		return;
769 
770 	spin_lock_irq(&dev_priv->irq_lock);
771 	dev_priv->hotplug.stats[pin].state = HPD_ENABLED;
772 	spin_unlock_irq(&dev_priv->irq_lock);
773 }
774