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 "i915_irq.h"
28 #include "intel_display_types.h"
29 #include "intel_hotplug.h"
30 
31 /**
32  * DOC: Hotplug
33  *
34  * Simply put, hotplug occurs when a display is connected to or disconnected
35  * from the system. However, there may be adapters and docking stations and
36  * Display Port short pulses and MST devices involved, complicating matters.
37  *
38  * Hotplug in i915 is handled in many different levels of abstraction.
39  *
40  * The platform dependent interrupt handling code in i915_irq.c enables,
41  * disables, and does preliminary handling of the interrupts. The interrupt
42  * handlers gather the hotplug detect (HPD) information from relevant registers
43  * into a platform independent mask of hotplug pins that have fired.
44  *
45  * The platform independent interrupt handler intel_hpd_irq_handler() in
46  * intel_hotplug.c does hotplug irq storm detection and mitigation, and passes
47  * further processing to appropriate bottom halves (Display Port specific and
48  * regular hotplug).
49  *
50  * The Display Port work function i915_digport_work_func() calls into
51  * intel_dp_hpd_pulse() via hooks, which handles DP short pulses and DP MST long
52  * pulses, with failures and non-MST long pulses triggering regular hotplug
53  * processing on the connector.
54  *
55  * The regular hotplug work function i915_hotplug_work_func() calls connector
56  * detect hooks, and, if connector status changes, triggers sending of hotplug
57  * uevent to userspace via drm_kms_helper_hotplug_event().
58  *
59  * Finally, the userspace is responsible for triggering a modeset upon receiving
60  * the hotplug uevent, disabling or enabling the crtc as needed.
61  *
62  * The hotplug interrupt storm detection and mitigation code keeps track of the
63  * number of interrupts per hotplug pin per a period of time, and if the number
64  * of interrupts exceeds a certain threshold, the interrupt is disabled for a
65  * while before being re-enabled. The intention is to mitigate issues raising
66  * from broken hardware triggering massive amounts of interrupts and grinding
67  * the system to a halt.
68  *
69  * Current implementation expects that hotplug interrupt storm will not be
70  * seen when display port sink is connected, hence on platforms whose DP
71  * callback is handled by i915_digport_work_func reenabling of hpd is not
72  * performed (it was never expected to be disabled in the first place ;) )
73  * this is specific to DP sinks handled by this routine and any other display
74  * such as HDMI or DVI enabled on the same port will have proper logic since
75  * it will use i915_hotplug_work_func where this logic is handled.
76  */
77 
78 /**
79  * intel_hpd_pin_default - return default pin associated with certain port.
80  * @dev_priv: private driver data pointer
81  * @port: the hpd port to get associated pin
82  *
83  * It is only valid and used by digital port encoder.
84  *
85  * Return pin that is associatade with @port.
86  */
intel_hpd_pin_default(struct drm_i915_private * dev_priv,enum port port)87 enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
88 				   enum port port)
89 {
90 	return HPD_PORT_A + port - PORT_A;
91 }
92 
93 /* Threshold == 5 for long IRQs, 50 for short */
94 #define HPD_STORM_DEFAULT_THRESHOLD	50
95 
96 #define HPD_STORM_DETECT_PERIOD		1000
97 #define HPD_STORM_REENABLE_DELAY	(2 * 60 * 1000)
98 #define HPD_RETRY_DELAY			1000
99 
100 static enum hpd_pin
intel_connector_hpd_pin(struct intel_connector * connector)101 intel_connector_hpd_pin(struct intel_connector *connector)
102 {
103 	struct intel_encoder *encoder = intel_attached_encoder(connector);
104 
105 	/*
106 	 * MST connectors get their encoder attached dynamically
107 	 * so need to make sure we have an encoder here. But since
108 	 * MST encoders have their hpd_pin set to HPD_NONE we don't
109 	 * have to special case them beyond that.
110 	 */
111 	return encoder ? encoder->hpd_pin : HPD_NONE;
112 }
113 
114 /**
115  * intel_hpd_irq_storm_detect - gather stats and detect HPD IRQ storm on a pin
116  * @dev_priv: private driver data pointer
117  * @pin: the pin to gather stats on
118  * @long_hpd: whether the HPD IRQ was long or short
119  *
120  * Gather stats about HPD IRQs from the specified @pin, and detect IRQ
121  * storms. Only the pin specific stats and state are changed, the caller is
122  * responsible for further action.
123  *
124  * The number of IRQs that are allowed within @HPD_STORM_DETECT_PERIOD is
125  * stored in @dev_priv->display.hotplug.hpd_storm_threshold which defaults to
126  * @HPD_STORM_DEFAULT_THRESHOLD. Long IRQs count as +10 to this threshold, and
127  * short IRQs count as +1. If this threshold is exceeded, it's considered an
128  * IRQ storm and the IRQ state is set to @HPD_MARK_DISABLED.
129  *
130  * By default, most systems will only count long IRQs towards
131  * &dev_priv->display.hotplug.hpd_storm_threshold. However, some older systems also
132  * suffer from short IRQ storms and must also track these. Because short IRQ
133  * storms are naturally caused by sideband interactions with DP MST devices,
134  * short IRQ detection is only enabled for systems without DP MST support.
135  * Systems which are new enough to support DP MST are far less likely to
136  * suffer from IRQ storms at all, so this is fine.
137  *
138  * The HPD threshold can be controlled through i915_hpd_storm_ctl in debugfs,
139  * and should only be adjusted for automated hotplug testing.
140  *
141  * Return true if an IRQ storm was detected on @pin.
142  */
intel_hpd_irq_storm_detect(struct drm_i915_private * dev_priv,enum hpd_pin pin,bool long_hpd)143 static bool intel_hpd_irq_storm_detect(struct drm_i915_private *dev_priv,
144 				       enum hpd_pin pin, bool long_hpd)
145 {
146 	struct intel_hotplug *hpd = &dev_priv->display.hotplug;
147 	unsigned long start = hpd->stats[pin].last_jiffies;
148 	unsigned long end = start + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD);
149 	const int increment = long_hpd ? 10 : 1;
150 	const int threshold = hpd->hpd_storm_threshold;
151 	bool storm = false;
152 
153 	if (!threshold ||
154 	    (!long_hpd && !dev_priv->display.hotplug.hpd_short_storm_enabled))
155 		return false;
156 
157 	if (!time_in_range(jiffies, start, end)) {
158 		hpd->stats[pin].last_jiffies = jiffies;
159 		hpd->stats[pin].count = 0;
160 	}
161 
162 	hpd->stats[pin].count += increment;
163 	if (hpd->stats[pin].count > threshold) {
164 		hpd->stats[pin].state = HPD_MARK_DISABLED;
165 		drm_dbg_kms(&dev_priv->drm,
166 			    "HPD interrupt storm detected on PIN %d\n", pin);
167 		storm = true;
168 	} else {
169 		drm_dbg_kms(&dev_priv->drm,
170 			    "Received HPD interrupt on PIN %d - cnt: %d\n",
171 			      pin,
172 			      hpd->stats[pin].count);
173 	}
174 
175 	return storm;
176 }
177 
178 static void
intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private * dev_priv)179 intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private *dev_priv)
180 {
181 	struct drm_connector_list_iter conn_iter;
182 	struct intel_connector *connector;
183 	bool hpd_disabled = false;
184 
185 	lockdep_assert_held(&dev_priv->irq_lock);
186 
187 	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
188 	for_each_intel_connector_iter(connector, &conn_iter) {
189 		enum hpd_pin pin;
190 
191 		if (connector->base.polled != DRM_CONNECTOR_POLL_HPD)
192 			continue;
193 
194 		pin = intel_connector_hpd_pin(connector);
195 		if (pin == HPD_NONE ||
196 		    dev_priv->display.hotplug.stats[pin].state != HPD_MARK_DISABLED)
197 			continue;
198 
199 		drm_info(&dev_priv->drm,
200 			 "HPD interrupt storm detected on connector %s: "
201 			 "switching from hotplug detection to polling\n",
202 			 connector->base.name);
203 
204 		dev_priv->display.hotplug.stats[pin].state = HPD_DISABLED;
205 		connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
206 			DRM_CONNECTOR_POLL_DISCONNECT;
207 		hpd_disabled = true;
208 	}
209 	drm_connector_list_iter_end(&conn_iter);
210 
211 	/* Enable polling and queue hotplug re-enabling. */
212 	if (hpd_disabled) {
213 		drm_kms_helper_poll_enable(&dev_priv->drm);
214 		mod_delayed_work(system_wq, &dev_priv->display.hotplug.reenable_work,
215 				 msecs_to_jiffies(HPD_STORM_REENABLE_DELAY));
216 	}
217 }
218 
intel_hpd_irq_storm_reenable_work(struct work_struct * work)219 static void intel_hpd_irq_storm_reenable_work(struct work_struct *work)
220 {
221 	struct drm_i915_private *dev_priv =
222 		container_of(work, typeof(*dev_priv),
223 			     display.hotplug.reenable_work.work);
224 	struct drm_connector_list_iter conn_iter;
225 	struct intel_connector *connector;
226 	intel_wakeref_t wakeref;
227 	enum hpd_pin pin;
228 
229 	wakeref = intel_runtime_pm_get(&dev_priv->runtime_pm);
230 
231 	spin_lock_irq(&dev_priv->irq_lock);
232 
233 	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
234 	for_each_intel_connector_iter(connector, &conn_iter) {
235 		pin = intel_connector_hpd_pin(connector);
236 		if (pin == HPD_NONE ||
237 		    dev_priv->display.hotplug.stats[pin].state != HPD_DISABLED)
238 			continue;
239 
240 		if (connector->base.polled != connector->polled)
241 			drm_dbg(&dev_priv->drm,
242 				"Reenabling HPD on connector %s\n",
243 				connector->base.name);
244 		connector->base.polled = connector->polled;
245 	}
246 	drm_connector_list_iter_end(&conn_iter);
247 
248 	for_each_hpd_pin(pin) {
249 		if (dev_priv->display.hotplug.stats[pin].state == HPD_DISABLED)
250 			dev_priv->display.hotplug.stats[pin].state = HPD_ENABLED;
251 	}
252 
253 	intel_hpd_irq_setup(dev_priv);
254 
255 	spin_unlock_irq(&dev_priv->irq_lock);
256 
257 	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
258 }
259 
260 enum intel_hotplug_state
intel_encoder_hotplug(struct intel_encoder * encoder,struct intel_connector * connector)261 intel_encoder_hotplug(struct intel_encoder *encoder,
262 		      struct intel_connector *connector)
263 {
264 	struct drm_device *dev = connector->base.dev;
265 	enum drm_connector_status old_status;
266 	u64 old_epoch_counter;
267 	bool ret = false;
268 
269 	drm_WARN_ON(dev, !mutex_is_locked(&dev->mode_config.mutex));
270 	old_status = connector->base.status;
271 	old_epoch_counter = connector->base.epoch_counter;
272 
273 	connector->base.status =
274 		drm_helper_probe_detect(&connector->base, NULL, false);
275 
276 	if (old_epoch_counter != connector->base.epoch_counter)
277 		ret = true;
278 
279 	if (ret) {
280 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s (epoch counter %llu->%llu)\n",
281 			    connector->base.base.id,
282 			    connector->base.name,
283 			    drm_get_connector_status_name(old_status),
284 			    drm_get_connector_status_name(connector->base.status),
285 			    old_epoch_counter,
286 			    connector->base.epoch_counter);
287 		return INTEL_HOTPLUG_CHANGED;
288 	}
289 	return INTEL_HOTPLUG_UNCHANGED;
290 }
291 
intel_encoder_has_hpd_pulse(struct intel_encoder * encoder)292 static bool intel_encoder_has_hpd_pulse(struct intel_encoder *encoder)
293 {
294 	return intel_encoder_is_dig_port(encoder) &&
295 		enc_to_dig_port(encoder)->hpd_pulse != NULL;
296 }
297 
i915_digport_work_func(struct work_struct * work)298 static void i915_digport_work_func(struct work_struct *work)
299 {
300 	struct drm_i915_private *dev_priv =
301 		container_of(work, struct drm_i915_private, display.hotplug.dig_port_work);
302 	u32 long_port_mask, short_port_mask;
303 	struct intel_encoder *encoder;
304 	u32 old_bits = 0;
305 
306 	spin_lock_irq(&dev_priv->irq_lock);
307 	long_port_mask = dev_priv->display.hotplug.long_port_mask;
308 	dev_priv->display.hotplug.long_port_mask = 0;
309 	short_port_mask = dev_priv->display.hotplug.short_port_mask;
310 	dev_priv->display.hotplug.short_port_mask = 0;
311 	spin_unlock_irq(&dev_priv->irq_lock);
312 
313 	for_each_intel_encoder(&dev_priv->drm, encoder) {
314 		struct intel_digital_port *dig_port;
315 		enum port port = encoder->port;
316 		bool long_hpd, short_hpd;
317 		enum irqreturn ret;
318 
319 		if (!intel_encoder_has_hpd_pulse(encoder))
320 			continue;
321 
322 		long_hpd = long_port_mask & BIT(port);
323 		short_hpd = short_port_mask & BIT(port);
324 
325 		if (!long_hpd && !short_hpd)
326 			continue;
327 
328 		dig_port = enc_to_dig_port(encoder);
329 
330 		ret = dig_port->hpd_pulse(dig_port, long_hpd);
331 		if (ret == IRQ_NONE) {
332 			/* fall back to old school hpd */
333 			old_bits |= BIT(encoder->hpd_pin);
334 		}
335 	}
336 
337 	if (old_bits) {
338 		spin_lock_irq(&dev_priv->irq_lock);
339 		dev_priv->display.hotplug.event_bits |= old_bits;
340 		spin_unlock_irq(&dev_priv->irq_lock);
341 		queue_delayed_work(system_wq, &dev_priv->display.hotplug.hotplug_work, 0);
342 	}
343 }
344 
345 /**
346  * intel_hpd_trigger_irq - trigger an hpd irq event for a port
347  * @dig_port: digital port
348  *
349  * Trigger an HPD interrupt event for the given port, emulating a short pulse
350  * generated by the sink, and schedule the dig port work to handle it.
351  */
intel_hpd_trigger_irq(struct intel_digital_port * dig_port)352 void intel_hpd_trigger_irq(struct intel_digital_port *dig_port)
353 {
354 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
355 
356 	spin_lock_irq(&i915->irq_lock);
357 	i915->display.hotplug.short_port_mask |= BIT(dig_port->base.port);
358 	spin_unlock_irq(&i915->irq_lock);
359 
360 	queue_work(i915->display.hotplug.dp_wq, &i915->display.hotplug.dig_port_work);
361 }
362 
363 /*
364  * Handle hotplug events outside the interrupt handler proper.
365  */
i915_hotplug_work_func(struct work_struct * work)366 static void i915_hotplug_work_func(struct work_struct *work)
367 {
368 	struct drm_i915_private *dev_priv =
369 		container_of(work, struct drm_i915_private,
370 			     display.hotplug.hotplug_work.work);
371 	struct drm_connector_list_iter conn_iter;
372 	struct intel_connector *connector;
373 	u32 changed = 0, retry = 0;
374 	u32 hpd_event_bits;
375 	u32 hpd_retry_bits;
376 
377 	mutex_lock(&dev_priv->drm.mode_config.mutex);
378 	drm_dbg_kms(&dev_priv->drm, "running encoder hotplug functions\n");
379 
380 	spin_lock_irq(&dev_priv->irq_lock);
381 
382 	hpd_event_bits = dev_priv->display.hotplug.event_bits;
383 	dev_priv->display.hotplug.event_bits = 0;
384 	hpd_retry_bits = dev_priv->display.hotplug.retry_bits;
385 	dev_priv->display.hotplug.retry_bits = 0;
386 
387 	/* Enable polling for connectors which had HPD IRQ storms */
388 	intel_hpd_irq_storm_switch_to_polling(dev_priv);
389 
390 	spin_unlock_irq(&dev_priv->irq_lock);
391 
392 	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
393 	for_each_intel_connector_iter(connector, &conn_iter) {
394 		enum hpd_pin pin;
395 		u32 hpd_bit;
396 
397 		pin = intel_connector_hpd_pin(connector);
398 		if (pin == HPD_NONE)
399 			continue;
400 
401 		hpd_bit = BIT(pin);
402 		if ((hpd_event_bits | hpd_retry_bits) & hpd_bit) {
403 			struct intel_encoder *encoder =
404 				intel_attached_encoder(connector);
405 
406 			if (hpd_event_bits & hpd_bit)
407 				connector->hotplug_retries = 0;
408 			else
409 				connector->hotplug_retries++;
410 
411 			drm_dbg_kms(&dev_priv->drm,
412 				    "Connector %s (pin %i) received hotplug event. (retry %d)\n",
413 				    connector->base.name, pin,
414 				    connector->hotplug_retries);
415 
416 			switch (encoder->hotplug(encoder, connector)) {
417 			case INTEL_HOTPLUG_UNCHANGED:
418 				break;
419 			case INTEL_HOTPLUG_CHANGED:
420 				changed |= hpd_bit;
421 				break;
422 			case INTEL_HOTPLUG_RETRY:
423 				retry |= hpd_bit;
424 				break;
425 			}
426 		}
427 	}
428 	drm_connector_list_iter_end(&conn_iter);
429 	mutex_unlock(&dev_priv->drm.mode_config.mutex);
430 
431 	if (changed)
432 		drm_kms_helper_hotplug_event(&dev_priv->drm);
433 
434 	/* Remove shared HPD pins that have changed */
435 	retry &= ~changed;
436 	if (retry) {
437 		spin_lock_irq(&dev_priv->irq_lock);
438 		dev_priv->display.hotplug.retry_bits |= retry;
439 		spin_unlock_irq(&dev_priv->irq_lock);
440 
441 		mod_delayed_work(system_wq, &dev_priv->display.hotplug.hotplug_work,
442 				 msecs_to_jiffies(HPD_RETRY_DELAY));
443 	}
444 }
445 
446 
447 /**
448  * intel_hpd_irq_handler - main hotplug irq handler
449  * @dev_priv: drm_i915_private
450  * @pin_mask: a mask of hpd pins that have triggered the irq
451  * @long_mask: a mask of hpd pins that may be long hpd pulses
452  *
453  * This is the main hotplug irq handler for all platforms. The platform specific
454  * irq handlers call the platform specific hotplug irq handlers, which read and
455  * decode the appropriate registers into bitmasks about hpd pins that have
456  * triggered (@pin_mask), and which of those pins may be long pulses
457  * (@long_mask). The @long_mask is ignored if the port corresponding to the pin
458  * is not a digital port.
459  *
460  * Here, we do hotplug irq storm detection and mitigation, and pass further
461  * processing to appropriate bottom halves.
462  */
intel_hpd_irq_handler(struct drm_i915_private * dev_priv,u32 pin_mask,u32 long_mask)463 void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
464 			   u32 pin_mask, u32 long_mask)
465 {
466 	struct intel_encoder *encoder;
467 	bool storm_detected = false;
468 	bool queue_dig = false, queue_hp = false;
469 	u32 long_hpd_pulse_mask = 0;
470 	u32 short_hpd_pulse_mask = 0;
471 	enum hpd_pin pin;
472 
473 	if (!pin_mask)
474 		return;
475 
476 	spin_lock(&dev_priv->irq_lock);
477 
478 	/*
479 	 * Determine whether ->hpd_pulse() exists for each pin, and
480 	 * whether we have a short or a long pulse. This is needed
481 	 * as each pin may have up to two encoders (HDMI and DP) and
482 	 * only the one of them (DP) will have ->hpd_pulse().
483 	 */
484 	for_each_intel_encoder(&dev_priv->drm, encoder) {
485 		enum port port = encoder->port;
486 		bool long_hpd;
487 
488 		pin = encoder->hpd_pin;
489 		if (!(BIT(pin) & pin_mask))
490 			continue;
491 
492 		if (!intel_encoder_has_hpd_pulse(encoder))
493 			continue;
494 
495 		long_hpd = long_mask & BIT(pin);
496 
497 		drm_dbg(&dev_priv->drm,
498 			"digital hpd on [ENCODER:%d:%s] - %s\n",
499 			encoder->base.base.id, encoder->base.name,
500 			long_hpd ? "long" : "short");
501 		queue_dig = true;
502 
503 		if (long_hpd) {
504 			long_hpd_pulse_mask |= BIT(pin);
505 			dev_priv->display.hotplug.long_port_mask |= BIT(port);
506 		} else {
507 			short_hpd_pulse_mask |= BIT(pin);
508 			dev_priv->display.hotplug.short_port_mask |= BIT(port);
509 		}
510 	}
511 
512 	/* Now process each pin just once */
513 	for_each_hpd_pin(pin) {
514 		bool long_hpd;
515 
516 		if (!(BIT(pin) & pin_mask))
517 			continue;
518 
519 		if (dev_priv->display.hotplug.stats[pin].state == HPD_DISABLED) {
520 			/*
521 			 * On GMCH platforms the interrupt mask bits only
522 			 * prevent irq generation, not the setting of the
523 			 * hotplug bits itself. So only WARN about unexpected
524 			 * interrupts on saner platforms.
525 			 */
526 			drm_WARN_ONCE(&dev_priv->drm, !HAS_GMCH(dev_priv),
527 				      "Received HPD interrupt on pin %d although disabled\n",
528 				      pin);
529 			continue;
530 		}
531 
532 		if (dev_priv->display.hotplug.stats[pin].state != HPD_ENABLED)
533 			continue;
534 
535 		/*
536 		 * Delegate to ->hpd_pulse() if one of the encoders for this
537 		 * pin has it, otherwise let the hotplug_work deal with this
538 		 * pin directly.
539 		 */
540 		if (((short_hpd_pulse_mask | long_hpd_pulse_mask) & BIT(pin))) {
541 			long_hpd = long_hpd_pulse_mask & BIT(pin);
542 		} else {
543 			dev_priv->display.hotplug.event_bits |= BIT(pin);
544 			long_hpd = true;
545 			queue_hp = true;
546 		}
547 
548 		if (intel_hpd_irq_storm_detect(dev_priv, pin, long_hpd)) {
549 			dev_priv->display.hotplug.event_bits &= ~BIT(pin);
550 			storm_detected = true;
551 			queue_hp = true;
552 		}
553 	}
554 
555 	/*
556 	 * Disable any IRQs that storms were detected on. Polling enablement
557 	 * happens later in our hotplug work.
558 	 */
559 	if (storm_detected)
560 		intel_hpd_irq_setup(dev_priv);
561 	spin_unlock(&dev_priv->irq_lock);
562 
563 	/*
564 	 * Our hotplug handler can grab modeset locks (by calling down into the
565 	 * fb helpers). Hence it must not be run on our own dev-priv->wq work
566 	 * queue for otherwise the flush_work in the pageflip code will
567 	 * deadlock.
568 	 */
569 	if (queue_dig)
570 		queue_work(dev_priv->display.hotplug.dp_wq, &dev_priv->display.hotplug.dig_port_work);
571 	if (queue_hp)
572 		queue_delayed_work(system_wq, &dev_priv->display.hotplug.hotplug_work, 0);
573 }
574 
575 /**
576  * intel_hpd_init - initializes and enables hpd support
577  * @dev_priv: i915 device instance
578  *
579  * This function enables the hotplug support. It requires that interrupts have
580  * already been enabled with intel_irq_init_hw(). From this point on hotplug and
581  * poll request can run concurrently to other code, so locking rules must be
582  * obeyed.
583  *
584  * This is a separate step from interrupt enabling to simplify the locking rules
585  * in the driver load and resume code.
586  *
587  * Also see: intel_hpd_poll_enable() and intel_hpd_poll_disable().
588  */
intel_hpd_init(struct drm_i915_private * dev_priv)589 void intel_hpd_init(struct drm_i915_private *dev_priv)
590 {
591 	int i;
592 
593 	if (!HAS_DISPLAY(dev_priv))
594 		return;
595 
596 	for_each_hpd_pin(i) {
597 		dev_priv->display.hotplug.stats[i].count = 0;
598 		dev_priv->display.hotplug.stats[i].state = HPD_ENABLED;
599 	}
600 
601 	/*
602 	 * Interrupt setup is already guaranteed to be single-threaded, this is
603 	 * just to make the assert_spin_locked checks happy.
604 	 */
605 	spin_lock_irq(&dev_priv->irq_lock);
606 	intel_hpd_irq_setup(dev_priv);
607 	spin_unlock_irq(&dev_priv->irq_lock);
608 }
609 
i915_hpd_poll_init_work(struct work_struct * work)610 static void i915_hpd_poll_init_work(struct work_struct *work)
611 {
612 	struct drm_i915_private *dev_priv =
613 		container_of(work, struct drm_i915_private,
614 			     display.hotplug.poll_init_work);
615 	struct drm_connector_list_iter conn_iter;
616 	struct intel_connector *connector;
617 	bool enabled;
618 
619 	mutex_lock(&dev_priv->drm.mode_config.mutex);
620 
621 	enabled = READ_ONCE(dev_priv->display.hotplug.poll_enabled);
622 
623 	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
624 	for_each_intel_connector_iter(connector, &conn_iter) {
625 		enum hpd_pin pin;
626 
627 		pin = intel_connector_hpd_pin(connector);
628 		if (pin == HPD_NONE)
629 			continue;
630 
631 		connector->base.polled = connector->polled;
632 
633 		if (enabled && connector->base.polled == DRM_CONNECTOR_POLL_HPD)
634 			connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
635 				DRM_CONNECTOR_POLL_DISCONNECT;
636 	}
637 	drm_connector_list_iter_end(&conn_iter);
638 
639 	if (enabled)
640 		drm_kms_helper_poll_enable(&dev_priv->drm);
641 
642 	mutex_unlock(&dev_priv->drm.mode_config.mutex);
643 
644 	/*
645 	 * We might have missed any hotplugs that happened while we were
646 	 * in the middle of disabling polling
647 	 */
648 	if (!enabled)
649 		drm_helper_hpd_irq_event(&dev_priv->drm);
650 }
651 
652 /**
653  * intel_hpd_poll_enable - enable polling for connectors with hpd
654  * @dev_priv: i915 device instance
655  *
656  * This function enables polling for all connectors which support HPD.
657  * Under certain conditions HPD may not be functional. On most Intel GPUs,
658  * this happens when we enter runtime suspend.
659  * On Valleyview and Cherryview systems, this also happens when we shut off all
660  * of the powerwells.
661  *
662  * Since this function can get called in contexts where we're already holding
663  * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
664  * worker.
665  *
666  * Also see: intel_hpd_init() and intel_hpd_poll_disable().
667  */
intel_hpd_poll_enable(struct drm_i915_private * dev_priv)668 void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
669 {
670 	if (!HAS_DISPLAY(dev_priv) ||
671 	    !INTEL_DISPLAY_ENABLED(dev_priv))
672 		return;
673 
674 	WRITE_ONCE(dev_priv->display.hotplug.poll_enabled, true);
675 
676 	/*
677 	 * We might already be holding dev->mode_config.mutex, so do this in a
678 	 * seperate worker
679 	 * As well, there's no issue if we race here since we always reschedule
680 	 * this worker anyway
681 	 */
682 	schedule_work(&dev_priv->display.hotplug.poll_init_work);
683 }
684 
685 /**
686  * intel_hpd_poll_disable - disable polling for connectors with hpd
687  * @dev_priv: i915 device instance
688  *
689  * This function disables polling for all connectors which support HPD.
690  * Under certain conditions HPD may not be functional. On most Intel GPUs,
691  * this happens when we enter runtime suspend.
692  * On Valleyview and Cherryview systems, this also happens when we shut off all
693  * of the powerwells.
694  *
695  * Since this function can get called in contexts where we're already holding
696  * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
697  * worker.
698  *
699  * Also used during driver init to initialize connector->polled
700  * appropriately for all connectors.
701  *
702  * Also see: intel_hpd_init() and intel_hpd_poll_enable().
703  */
intel_hpd_poll_disable(struct drm_i915_private * dev_priv)704 void intel_hpd_poll_disable(struct drm_i915_private *dev_priv)
705 {
706 	if (!HAS_DISPLAY(dev_priv))
707 		return;
708 
709 	WRITE_ONCE(dev_priv->display.hotplug.poll_enabled, false);
710 	schedule_work(&dev_priv->display.hotplug.poll_init_work);
711 }
712 
intel_hpd_init_early(struct drm_i915_private * i915)713 void intel_hpd_init_early(struct drm_i915_private *i915)
714 {
715 	INIT_DELAYED_WORK(&i915->display.hotplug.hotplug_work,
716 			  i915_hotplug_work_func);
717 	INIT_WORK(&i915->display.hotplug.dig_port_work, i915_digport_work_func);
718 	INIT_WORK(&i915->display.hotplug.poll_init_work, i915_hpd_poll_init_work);
719 	INIT_DELAYED_WORK(&i915->display.hotplug.reenable_work,
720 			  intel_hpd_irq_storm_reenable_work);
721 
722 	i915->display.hotplug.hpd_storm_threshold = HPD_STORM_DEFAULT_THRESHOLD;
723 	/* If we have MST support, we want to avoid doing short HPD IRQ storm
724 	 * detection, as short HPD storms will occur as a natural part of
725 	 * sideband messaging with MST.
726 	 * On older platforms however, IRQ storms can occur with both long and
727 	 * short pulses, as seen on some G4x systems.
728 	 */
729 	i915->display.hotplug.hpd_short_storm_enabled = !HAS_DP_MST(i915);
730 }
731 
intel_hpd_cancel_work(struct drm_i915_private * dev_priv)732 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
733 {
734 	if (!HAS_DISPLAY(dev_priv))
735 		return;
736 
737 	spin_lock_irq(&dev_priv->irq_lock);
738 
739 	dev_priv->display.hotplug.long_port_mask = 0;
740 	dev_priv->display.hotplug.short_port_mask = 0;
741 	dev_priv->display.hotplug.event_bits = 0;
742 	dev_priv->display.hotplug.retry_bits = 0;
743 
744 	spin_unlock_irq(&dev_priv->irq_lock);
745 
746 	cancel_work_sync(&dev_priv->display.hotplug.dig_port_work);
747 	cancel_delayed_work_sync(&dev_priv->display.hotplug.hotplug_work);
748 	cancel_work_sync(&dev_priv->display.hotplug.poll_init_work);
749 	cancel_delayed_work_sync(&dev_priv->display.hotplug.reenable_work);
750 }
751 
intel_hpd_disable(struct drm_i915_private * dev_priv,enum hpd_pin pin)752 bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
753 {
754 	bool ret = false;
755 
756 	if (pin == HPD_NONE)
757 		return false;
758 
759 	spin_lock_irq(&dev_priv->irq_lock);
760 	if (dev_priv->display.hotplug.stats[pin].state == HPD_ENABLED) {
761 		dev_priv->display.hotplug.stats[pin].state = HPD_DISABLED;
762 		ret = true;
763 	}
764 	spin_unlock_irq(&dev_priv->irq_lock);
765 
766 	return ret;
767 }
768 
intel_hpd_enable(struct drm_i915_private * dev_priv,enum hpd_pin pin)769 void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
770 {
771 	if (pin == HPD_NONE)
772 		return;
773 
774 	spin_lock_irq(&dev_priv->irq_lock);
775 	dev_priv->display.hotplug.stats[pin].state = HPD_ENABLED;
776 	spin_unlock_irq(&dev_priv->irq_lock);
777 }
778 
i915_hpd_storm_ctl_show(struct seq_file * m,void * data)779 static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
780 {
781 	struct drm_i915_private *dev_priv = m->private;
782 	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
783 
784 	/* Synchronize with everything first in case there's been an HPD
785 	 * storm, but we haven't finished handling it in the kernel yet
786 	 */
787 	intel_synchronize_irq(dev_priv);
788 	flush_work(&dev_priv->display.hotplug.dig_port_work);
789 	flush_delayed_work(&dev_priv->display.hotplug.hotplug_work);
790 
791 	seq_printf(m, "Threshold: %d\n", hotplug->hpd_storm_threshold);
792 	seq_printf(m, "Detected: %s\n",
793 		   str_yes_no(delayed_work_pending(&hotplug->reenable_work)));
794 
795 	return 0;
796 }
797 
i915_hpd_storm_ctl_write(struct file * file,const char __user * ubuf,size_t len,loff_t * offp)798 static ssize_t i915_hpd_storm_ctl_write(struct file *file,
799 					const char __user *ubuf, size_t len,
800 					loff_t *offp)
801 {
802 	struct seq_file *m = file->private_data;
803 	struct drm_i915_private *dev_priv = m->private;
804 	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
805 	unsigned int new_threshold;
806 	int i;
807 	char *newline;
808 	char tmp[16];
809 
810 	if (len >= sizeof(tmp))
811 		return -EINVAL;
812 
813 	if (copy_from_user(tmp, ubuf, len))
814 		return -EFAULT;
815 
816 	tmp[len] = '\0';
817 
818 	/* Strip newline, if any */
819 	newline = strchr(tmp, '\n');
820 	if (newline)
821 		*newline = '\0';
822 
823 	if (strcmp(tmp, "reset") == 0)
824 		new_threshold = HPD_STORM_DEFAULT_THRESHOLD;
825 	else if (kstrtouint(tmp, 10, &new_threshold) != 0)
826 		return -EINVAL;
827 
828 	if (new_threshold > 0)
829 		drm_dbg_kms(&dev_priv->drm,
830 			    "Setting HPD storm detection threshold to %d\n",
831 			    new_threshold);
832 	else
833 		drm_dbg_kms(&dev_priv->drm, "Disabling HPD storm detection\n");
834 
835 	spin_lock_irq(&dev_priv->irq_lock);
836 	hotplug->hpd_storm_threshold = new_threshold;
837 	/* Reset the HPD storm stats so we don't accidentally trigger a storm */
838 	for_each_hpd_pin(i)
839 		hotplug->stats[i].count = 0;
840 	spin_unlock_irq(&dev_priv->irq_lock);
841 
842 	/* Re-enable hpd immediately if we were in an irq storm */
843 	flush_delayed_work(&dev_priv->display.hotplug.reenable_work);
844 
845 	return len;
846 }
847 
i915_hpd_storm_ctl_open(struct inode * inode,struct file * file)848 static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
849 {
850 	return single_open(file, i915_hpd_storm_ctl_show, inode->i_private);
851 }
852 
853 static const struct file_operations i915_hpd_storm_ctl_fops = {
854 	.owner = THIS_MODULE,
855 	.open = i915_hpd_storm_ctl_open,
856 	.read = seq_read,
857 	.llseek = seq_lseek,
858 	.release = single_release,
859 	.write = i915_hpd_storm_ctl_write
860 };
861 
i915_hpd_short_storm_ctl_show(struct seq_file * m,void * data)862 static int i915_hpd_short_storm_ctl_show(struct seq_file *m, void *data)
863 {
864 	struct drm_i915_private *dev_priv = m->private;
865 
866 	seq_printf(m, "Enabled: %s\n",
867 		   str_yes_no(dev_priv->display.hotplug.hpd_short_storm_enabled));
868 
869 	return 0;
870 }
871 
872 static int
i915_hpd_short_storm_ctl_open(struct inode * inode,struct file * file)873 i915_hpd_short_storm_ctl_open(struct inode *inode, struct file *file)
874 {
875 	return single_open(file, i915_hpd_short_storm_ctl_show,
876 			   inode->i_private);
877 }
878 
i915_hpd_short_storm_ctl_write(struct file * file,const char __user * ubuf,size_t len,loff_t * offp)879 static ssize_t i915_hpd_short_storm_ctl_write(struct file *file,
880 					      const char __user *ubuf,
881 					      size_t len, loff_t *offp)
882 {
883 	struct seq_file *m = file->private_data;
884 	struct drm_i915_private *dev_priv = m->private;
885 	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
886 	char *newline;
887 	char tmp[16];
888 	int i;
889 	bool new_state;
890 
891 	if (len >= sizeof(tmp))
892 		return -EINVAL;
893 
894 	if (copy_from_user(tmp, ubuf, len))
895 		return -EFAULT;
896 
897 	tmp[len] = '\0';
898 
899 	/* Strip newline, if any */
900 	newline = strchr(tmp, '\n');
901 	if (newline)
902 		*newline = '\0';
903 
904 	/* Reset to the "default" state for this system */
905 	if (strcmp(tmp, "reset") == 0)
906 		new_state = !HAS_DP_MST(dev_priv);
907 	else if (kstrtobool(tmp, &new_state) != 0)
908 		return -EINVAL;
909 
910 	drm_dbg_kms(&dev_priv->drm, "%sabling HPD short storm detection\n",
911 		    new_state ? "En" : "Dis");
912 
913 	spin_lock_irq(&dev_priv->irq_lock);
914 	hotplug->hpd_short_storm_enabled = new_state;
915 	/* Reset the HPD storm stats so we don't accidentally trigger a storm */
916 	for_each_hpd_pin(i)
917 		hotplug->stats[i].count = 0;
918 	spin_unlock_irq(&dev_priv->irq_lock);
919 
920 	/* Re-enable hpd immediately if we were in an irq storm */
921 	flush_delayed_work(&dev_priv->display.hotplug.reenable_work);
922 
923 	return len;
924 }
925 
926 static const struct file_operations i915_hpd_short_storm_ctl_fops = {
927 	.owner = THIS_MODULE,
928 	.open = i915_hpd_short_storm_ctl_open,
929 	.read = seq_read,
930 	.llseek = seq_lseek,
931 	.release = single_release,
932 	.write = i915_hpd_short_storm_ctl_write,
933 };
934 
intel_hpd_debugfs_register(struct drm_i915_private * i915)935 void intel_hpd_debugfs_register(struct drm_i915_private *i915)
936 {
937 	struct drm_minor *minor = i915->drm.primary;
938 
939 	debugfs_create_file("i915_hpd_storm_ctl", 0644, minor->debugfs_root,
940 			    i915, &i915_hpd_storm_ctl_fops);
941 	debugfs_create_file("i915_hpd_short_storm_ctl", 0644, minor->debugfs_root,
942 			    i915, &i915_hpd_short_storm_ctl_fops);
943 }
944