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/debugfs.h>
  25#include <linux/kernel.h>
  26
  27#include <drm/drm_probe_helper.h>
  28
  29#include "i915_drv.h"
  30#include "i915_irq.h"
  31#include "intel_display_power.h"
  32#include "intel_display_types.h"
  33#include "intel_hotplug.h"
  34#include "intel_hotplug_irq.h"
  35
  36/**
  37 * DOC: Hotplug
  38 *
  39 * Simply put, hotplug occurs when a display is connected to or disconnected
  40 * from the system. However, there may be adapters and docking stations and
  41 * Display Port short pulses and MST devices involved, complicating matters.
  42 *
  43 * Hotplug in i915 is handled in many different levels of abstraction.
  44 *
  45 * The platform dependent interrupt handling code in i915_irq.c enables,
  46 * disables, and does preliminary handling of the interrupts. The interrupt
  47 * handlers gather the hotplug detect (HPD) information from relevant registers
  48 * into a platform independent mask of hotplug pins that have fired.
  49 *
  50 * The platform independent interrupt handler intel_hpd_irq_handler() in
  51 * intel_hotplug.c does hotplug irq storm detection and mitigation, and passes
  52 * further processing to appropriate bottom halves (Display Port specific and
  53 * regular hotplug).
  54 *
  55 * The Display Port work function i915_digport_work_func() calls into
  56 * intel_dp_hpd_pulse() via hooks, which handles DP short pulses and DP MST long
  57 * pulses, with failures and non-MST long pulses triggering regular hotplug
  58 * processing on the connector.
  59 *
  60 * The regular hotplug work function i915_hotplug_work_func() calls connector
  61 * detect hooks, and, if connector status changes, triggers sending of hotplug
  62 * uevent to userspace via drm_kms_helper_hotplug_event().
  63 *
  64 * Finally, the userspace is responsible for triggering a modeset upon receiving
  65 * the hotplug uevent, disabling or enabling the crtc as needed.
  66 *
  67 * The hotplug interrupt storm detection and mitigation code keeps track of the
  68 * number of interrupts per hotplug pin per a period of time, and if the number
  69 * of interrupts exceeds a certain threshold, the interrupt is disabled for a
  70 * while before being re-enabled. The intention is to mitigate issues raising
  71 * from broken hardware triggering massive amounts of interrupts and grinding
  72 * the system to a halt.
  73 *
  74 * Current implementation expects that hotplug interrupt storm will not be
  75 * seen when display port sink is connected, hence on platforms whose DP
  76 * callback is handled by i915_digport_work_func reenabling of hpd is not
  77 * performed (it was never expected to be disabled in the first place ;) )
  78 * this is specific to DP sinks handled by this routine and any other display
  79 * such as HDMI or DVI enabled on the same port will have proper logic since
  80 * it will use i915_hotplug_work_func where this logic is handled.
  81 */
  82
  83/**
  84 * intel_hpd_pin_default - return default pin associated with certain port.
  85 * @dev_priv: private driver data pointer
  86 * @port: the hpd port to get associated pin
  87 *
  88 * It is only valid and used by digital port encoder.
  89 *
  90 * Return pin that is associatade with @port.
  91 */
  92enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
  93				   enum port port)
  94{
  95	return HPD_PORT_A + port - PORT_A;
  96}
  97
  98/* Threshold == 5 for long IRQs, 50 for short */
  99#define HPD_STORM_DEFAULT_THRESHOLD	50
 100
 101#define HPD_STORM_DETECT_PERIOD		1000
 102#define HPD_STORM_REENABLE_DELAY	(2 * 60 * 1000)
 103#define HPD_RETRY_DELAY			1000
 104
 105static enum hpd_pin
 106intel_connector_hpd_pin(struct intel_connector *connector)
 107{
 108	struct intel_encoder *encoder = intel_attached_encoder(connector);
 109
 110	/*
 111	 * MST connectors get their encoder attached dynamically
 112	 * so need to make sure we have an encoder here. But since
 113	 * MST encoders have their hpd_pin set to HPD_NONE we don't
 114	 * have to special case them beyond that.
 115	 */
 116	return encoder ? encoder->hpd_pin : HPD_NONE;
 117}
 118
 119/**
 120 * intel_hpd_irq_storm_detect - gather stats and detect HPD IRQ storm on a pin
 121 * @dev_priv: private driver data pointer
 122 * @pin: the pin to gather stats on
 123 * @long_hpd: whether the HPD IRQ was long or short
 124 *
 125 * Gather stats about HPD IRQs from the specified @pin, and detect IRQ
 126 * storms. Only the pin specific stats and state are changed, the caller is
 127 * responsible for further action.
 128 *
 129 * The number of IRQs that are allowed within @HPD_STORM_DETECT_PERIOD is
 130 * stored in @dev_priv->display.hotplug.hpd_storm_threshold which defaults to
 131 * @HPD_STORM_DEFAULT_THRESHOLD. Long IRQs count as +10 to this threshold, and
 132 * short IRQs count as +1. If this threshold is exceeded, it's considered an
 133 * IRQ storm and the IRQ state is set to @HPD_MARK_DISABLED.
 134 *
 135 * By default, most systems will only count long IRQs towards
 136 * &dev_priv->display.hotplug.hpd_storm_threshold. However, some older systems also
 137 * suffer from short IRQ storms and must also track these. Because short IRQ
 138 * storms are naturally caused by sideband interactions with DP MST devices,
 139 * short IRQ detection is only enabled for systems without DP MST support.
 140 * Systems which are new enough to support DP MST are far less likely to
 141 * suffer from IRQ storms at all, so this is fine.
 142 *
 143 * The HPD threshold can be controlled through i915_hpd_storm_ctl in debugfs,
 144 * and should only be adjusted for automated hotplug testing.
 145 *
 146 * Return true if an IRQ storm was detected on @pin.
 147 */
 148static bool intel_hpd_irq_storm_detect(struct drm_i915_private *dev_priv,
 149				       enum hpd_pin pin, bool long_hpd)
 150{
 151	struct intel_hotplug *hpd = &dev_priv->display.hotplug;
 152	unsigned long start = hpd->stats[pin].last_jiffies;
 153	unsigned long end = start + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD);
 154	const int increment = long_hpd ? 10 : 1;
 155	const int threshold = hpd->hpd_storm_threshold;
 156	bool storm = false;
 157
 158	if (!threshold ||
 159	    (!long_hpd && !dev_priv->display.hotplug.hpd_short_storm_enabled))
 160		return false;
 161
 162	if (!time_in_range(jiffies, start, end)) {
 163		hpd->stats[pin].last_jiffies = jiffies;
 164		hpd->stats[pin].count = 0;
 165	}
 166
 167	hpd->stats[pin].count += increment;
 168	if (hpd->stats[pin].count > threshold) {
 169		hpd->stats[pin].state = HPD_MARK_DISABLED;
 170		drm_dbg_kms(&dev_priv->drm,
 171			    "HPD interrupt storm detected on PIN %d\n", pin);
 172		storm = true;
 173	} else {
 174		drm_dbg_kms(&dev_priv->drm,
 175			    "Received HPD interrupt on PIN %d - cnt: %d\n",
 176			      pin,
 177			      hpd->stats[pin].count);
 178	}
 179
 180	return storm;
 181}
 182
 183static bool detection_work_enabled(struct drm_i915_private *i915)
 184{
 185	lockdep_assert_held(&i915->irq_lock);
 186
 187	return i915->display.hotplug.detection_work_enabled;
 188}
 189
 190static bool
 191mod_delayed_detection_work(struct drm_i915_private *i915, struct delayed_work *work, int delay)
 192{
 193	lockdep_assert_held(&i915->irq_lock);
 194
 195	if (!detection_work_enabled(i915))
 196		return false;
 197
 198	return mod_delayed_work(i915->unordered_wq, work, delay);
 199}
 200
 201static bool
 202queue_delayed_detection_work(struct drm_i915_private *i915, struct delayed_work *work, int delay)
 203{
 204	lockdep_assert_held(&i915->irq_lock);
 205
 206	if (!detection_work_enabled(i915))
 207		return false;
 208
 209	return queue_delayed_work(i915->unordered_wq, work, delay);
 210}
 211
 212static bool
 213queue_detection_work(struct drm_i915_private *i915, struct work_struct *work)
 214{
 215	lockdep_assert_held(&i915->irq_lock);
 216
 217	if (!detection_work_enabled(i915))
 218		return false;
 219
 220	return queue_work(i915->unordered_wq, work);
 221}
 222
 223static void
 224intel_hpd_irq_storm_switch_to_polling(struct drm_i915_private *dev_priv)
 225{
 
 226	struct drm_connector_list_iter conn_iter;
 227	struct intel_connector *connector;
 228	bool hpd_disabled = false;
 229
 230	lockdep_assert_held(&dev_priv->irq_lock);
 231
 232	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
 233	for_each_intel_connector_iter(connector, &conn_iter) {
 234		enum hpd_pin pin;
 235
 236		if (connector->base.polled != DRM_CONNECTOR_POLL_HPD)
 237			continue;
 238
 239		pin = intel_connector_hpd_pin(connector);
 240		if (pin == HPD_NONE ||
 241		    dev_priv->display.hotplug.stats[pin].state != HPD_MARK_DISABLED)
 242			continue;
 243
 244		drm_info(&dev_priv->drm,
 245			 "HPD interrupt storm detected on connector %s: "
 246			 "switching from hotplug detection to polling\n",
 247			 connector->base.name);
 248
 249		dev_priv->display.hotplug.stats[pin].state = HPD_DISABLED;
 250		connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
 251			DRM_CONNECTOR_POLL_DISCONNECT;
 252		hpd_disabled = true;
 253	}
 254	drm_connector_list_iter_end(&conn_iter);
 255
 256	/* Enable polling and queue hotplug re-enabling. */
 257	if (hpd_disabled) {
 258		drm_kms_helper_poll_reschedule(&dev_priv->drm);
 259		mod_delayed_detection_work(dev_priv,
 260					   &dev_priv->display.hotplug.reenable_work,
 261					   msecs_to_jiffies(HPD_STORM_REENABLE_DELAY));
 262	}
 263}
 264
 
 
 
 
 
 
 265static void intel_hpd_irq_storm_reenable_work(struct work_struct *work)
 266{
 267	struct drm_i915_private *dev_priv =
 268		container_of(work, typeof(*dev_priv),
 269			     display.hotplug.reenable_work.work);
 
 270	struct drm_connector_list_iter conn_iter;
 271	struct intel_connector *connector;
 272	intel_wakeref_t wakeref;
 273	enum hpd_pin pin;
 274
 275	wakeref = intel_runtime_pm_get(&dev_priv->runtime_pm);
 276
 277	spin_lock_irq(&dev_priv->irq_lock);
 278
 279	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
 280	for_each_intel_connector_iter(connector, &conn_iter) {
 281		pin = intel_connector_hpd_pin(connector);
 282		if (pin == HPD_NONE ||
 283		    dev_priv->display.hotplug.stats[pin].state != HPD_DISABLED)
 284			continue;
 285
 286		if (connector->base.polled != connector->polled)
 287			drm_dbg(&dev_priv->drm,
 288				"Reenabling HPD on connector %s\n",
 289				connector->base.name);
 290		connector->base.polled = connector->polled;
 291	}
 292	drm_connector_list_iter_end(&conn_iter);
 293
 294	for_each_hpd_pin(pin) {
 295		if (dev_priv->display.hotplug.stats[pin].state == HPD_DISABLED)
 296			dev_priv->display.hotplug.stats[pin].state = HPD_ENABLED;
 297	}
 298
 299	intel_hpd_irq_setup(dev_priv);
 300
 301	spin_unlock_irq(&dev_priv->irq_lock);
 302
 303	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
 304}
 305
 306static enum intel_hotplug_state
 307intel_hotplug_detect_connector(struct intel_connector *connector)
 
 308{
 309	struct drm_device *dev = connector->base.dev;
 310	enum drm_connector_status old_status;
 311	u64 old_epoch_counter;
 312	int status;
 313	bool ret = false;
 314
 315	drm_WARN_ON(dev, !mutex_is_locked(&dev->mode_config.mutex));
 316	old_status = connector->base.status;
 317	old_epoch_counter = connector->base.epoch_counter;
 318
 319	status = drm_helper_probe_detect(&connector->base, NULL, false);
 320	if (!connector->base.force)
 321		connector->base.status = status;
 322
 323	if (old_epoch_counter != connector->base.epoch_counter)
 324		ret = true;
 325
 326	if (ret) {
 327		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s (epoch counter %llu->%llu)\n",
 328			    connector->base.base.id,
 329			    connector->base.name,
 330			    drm_get_connector_status_name(old_status),
 331			    drm_get_connector_status_name(connector->base.status),
 332			    old_epoch_counter,
 333			    connector->base.epoch_counter);
 334		return INTEL_HOTPLUG_CHANGED;
 335	}
 336	return INTEL_HOTPLUG_UNCHANGED;
 337}
 338
 339enum intel_hotplug_state
 340intel_encoder_hotplug(struct intel_encoder *encoder,
 341		      struct intel_connector *connector)
 342{
 343	return intel_hotplug_detect_connector(connector);
 344}
 345
 346static bool intel_encoder_has_hpd_pulse(struct intel_encoder *encoder)
 347{
 348	return intel_encoder_is_dig_port(encoder) &&
 349		enc_to_dig_port(encoder)->hpd_pulse != NULL;
 350}
 351
 352static void i915_digport_work_func(struct work_struct *work)
 353{
 354	struct drm_i915_private *dev_priv =
 355		container_of(work, struct drm_i915_private, display.hotplug.dig_port_work);
 356	u32 long_port_mask, short_port_mask;
 357	struct intel_encoder *encoder;
 358	u32 old_bits = 0;
 359
 360	spin_lock_irq(&dev_priv->irq_lock);
 361	long_port_mask = dev_priv->display.hotplug.long_port_mask;
 362	dev_priv->display.hotplug.long_port_mask = 0;
 363	short_port_mask = dev_priv->display.hotplug.short_port_mask;
 364	dev_priv->display.hotplug.short_port_mask = 0;
 365	spin_unlock_irq(&dev_priv->irq_lock);
 366
 367	for_each_intel_encoder(&dev_priv->drm, encoder) {
 368		struct intel_digital_port *dig_port;
 369		enum port port = encoder->port;
 370		bool long_hpd, short_hpd;
 371		enum irqreturn ret;
 372
 373		if (!intel_encoder_has_hpd_pulse(encoder))
 374			continue;
 375
 376		long_hpd = long_port_mask & BIT(port);
 377		short_hpd = short_port_mask & BIT(port);
 378
 379		if (!long_hpd && !short_hpd)
 380			continue;
 381
 382		dig_port = enc_to_dig_port(encoder);
 383
 384		ret = dig_port->hpd_pulse(dig_port, long_hpd);
 385		if (ret == IRQ_NONE) {
 386			/* fall back to old school hpd */
 387			old_bits |= BIT(encoder->hpd_pin);
 388		}
 389	}
 390
 391	if (old_bits) {
 392		spin_lock_irq(&dev_priv->irq_lock);
 393		dev_priv->display.hotplug.event_bits |= old_bits;
 394		queue_delayed_detection_work(dev_priv,
 395					     &dev_priv->display.hotplug.hotplug_work, 0);
 396		spin_unlock_irq(&dev_priv->irq_lock);
 
 397	}
 398}
 399
 400/**
 401 * intel_hpd_trigger_irq - trigger an hpd irq event for a port
 402 * @dig_port: digital port
 403 *
 404 * Trigger an HPD interrupt event for the given port, emulating a short pulse
 405 * generated by the sink, and schedule the dig port work to handle it.
 406 */
 407void intel_hpd_trigger_irq(struct intel_digital_port *dig_port)
 408{
 409	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
 410
 411	spin_lock_irq(&i915->irq_lock);
 412	i915->display.hotplug.short_port_mask |= BIT(dig_port->base.port);
 413	spin_unlock_irq(&i915->irq_lock);
 414
 415	queue_work(i915->display.hotplug.dp_wq, &i915->display.hotplug.dig_port_work);
 416}
 417
 418/*
 419 * Handle hotplug events outside the interrupt handler proper.
 420 */
 421static void i915_hotplug_work_func(struct work_struct *work)
 422{
 423	struct drm_i915_private *dev_priv =
 424		container_of(work, struct drm_i915_private,
 425			     display.hotplug.hotplug_work.work);
 
 426	struct drm_connector_list_iter conn_iter;
 427	struct intel_connector *connector;
 428	u32 changed = 0, retry = 0;
 429	u32 hpd_event_bits;
 430	u32 hpd_retry_bits;
 431	struct drm_connector *first_changed_connector = NULL;
 432	int changed_connectors = 0;
 433
 434	mutex_lock(&dev_priv->drm.mode_config.mutex);
 435	drm_dbg_kms(&dev_priv->drm, "running encoder hotplug functions\n");
 436
 437	spin_lock_irq(&dev_priv->irq_lock);
 438
 439	hpd_event_bits = dev_priv->display.hotplug.event_bits;
 440	dev_priv->display.hotplug.event_bits = 0;
 441	hpd_retry_bits = dev_priv->display.hotplug.retry_bits;
 442	dev_priv->display.hotplug.retry_bits = 0;
 443
 444	/* Enable polling for connectors which had HPD IRQ storms */
 445	intel_hpd_irq_storm_switch_to_polling(dev_priv);
 446
 447	spin_unlock_irq(&dev_priv->irq_lock);
 448
 449	/* Skip calling encode hotplug handlers if ignore long HPD set*/
 450	if (dev_priv->display.hotplug.ignore_long_hpd) {
 451		drm_dbg_kms(&dev_priv->drm, "Ignore HPD flag on - skip encoder hotplug handlers\n");
 452		mutex_unlock(&dev_priv->drm.mode_config.mutex);
 453		return;
 454	}
 455
 456	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
 457	for_each_intel_connector_iter(connector, &conn_iter) {
 458		enum hpd_pin pin;
 459		u32 hpd_bit;
 460
 461		pin = intel_connector_hpd_pin(connector);
 462		if (pin == HPD_NONE)
 463			continue;
 464
 465		hpd_bit = BIT(pin);
 466		if ((hpd_event_bits | hpd_retry_bits) & hpd_bit) {
 467			struct intel_encoder *encoder =
 468				intel_attached_encoder(connector);
 469
 470			if (hpd_event_bits & hpd_bit)
 471				connector->hotplug_retries = 0;
 472			else
 473				connector->hotplug_retries++;
 474
 475			drm_dbg_kms(&dev_priv->drm,
 476				    "Connector %s (pin %i) received hotplug event. (retry %d)\n",
 477				    connector->base.name, pin,
 478				    connector->hotplug_retries);
 479
 480			switch (encoder->hotplug(encoder, connector)) {
 481			case INTEL_HOTPLUG_UNCHANGED:
 482				break;
 483			case INTEL_HOTPLUG_CHANGED:
 484				changed |= hpd_bit;
 485				changed_connectors++;
 486				if (!first_changed_connector) {
 487					drm_connector_get(&connector->base);
 488					first_changed_connector = &connector->base;
 489				}
 490				break;
 491			case INTEL_HOTPLUG_RETRY:
 492				retry |= hpd_bit;
 493				break;
 494			}
 495		}
 496	}
 497	drm_connector_list_iter_end(&conn_iter);
 498	mutex_unlock(&dev_priv->drm.mode_config.mutex);
 499
 500	if (changed_connectors == 1)
 501		drm_kms_helper_connector_hotplug_event(first_changed_connector);
 502	else if (changed_connectors > 0)
 503		drm_kms_helper_hotplug_event(&dev_priv->drm);
 504
 505	if (first_changed_connector)
 506		drm_connector_put(first_changed_connector);
 507
 508	/* Remove shared HPD pins that have changed */
 509	retry &= ~changed;
 510	if (retry) {
 511		spin_lock_irq(&dev_priv->irq_lock);
 512		dev_priv->display.hotplug.retry_bits |= retry;
 513
 514		mod_delayed_detection_work(dev_priv,
 515					   &dev_priv->display.hotplug.hotplug_work,
 516					   msecs_to_jiffies(HPD_RETRY_DELAY));
 517		spin_unlock_irq(&dev_priv->irq_lock);
 
 
 
 518	}
 519}
 520
 521
 522/**
 523 * intel_hpd_irq_handler - main hotplug irq handler
 524 * @dev_priv: drm_i915_private
 525 * @pin_mask: a mask of hpd pins that have triggered the irq
 526 * @long_mask: a mask of hpd pins that may be long hpd pulses
 527 *
 528 * This is the main hotplug irq handler for all platforms. The platform specific
 529 * irq handlers call the platform specific hotplug irq handlers, which read and
 530 * decode the appropriate registers into bitmasks about hpd pins that have
 531 * triggered (@pin_mask), and which of those pins may be long pulses
 532 * (@long_mask). The @long_mask is ignored if the port corresponding to the pin
 533 * is not a digital port.
 534 *
 535 * Here, we do hotplug irq storm detection and mitigation, and pass further
 536 * processing to appropriate bottom halves.
 537 */
 538void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
 539			   u32 pin_mask, u32 long_mask)
 540{
 541	struct intel_encoder *encoder;
 542	bool storm_detected = false;
 543	bool queue_dig = false, queue_hp = false;
 544	u32 long_hpd_pulse_mask = 0;
 545	u32 short_hpd_pulse_mask = 0;
 546	enum hpd_pin pin;
 547
 548	if (!pin_mask)
 549		return;
 550
 551	spin_lock(&dev_priv->irq_lock);
 552
 553	/*
 554	 * Determine whether ->hpd_pulse() exists for each pin, and
 555	 * whether we have a short or a long pulse. This is needed
 556	 * as each pin may have up to two encoders (HDMI and DP) and
 557	 * only the one of them (DP) will have ->hpd_pulse().
 558	 */
 559	for_each_intel_encoder(&dev_priv->drm, encoder) {
 560		enum port port = encoder->port;
 561		bool long_hpd;
 562
 563		pin = encoder->hpd_pin;
 564		if (!(BIT(pin) & pin_mask))
 565			continue;
 566
 567		if (!intel_encoder_has_hpd_pulse(encoder))
 568			continue;
 569
 570		long_hpd = long_mask & BIT(pin);
 571
 572		drm_dbg(&dev_priv->drm,
 573			"digital hpd on [ENCODER:%d:%s] - %s\n",
 574			encoder->base.base.id, encoder->base.name,
 575			long_hpd ? "long" : "short");
 576		queue_dig = true;
 577
 578		if (long_hpd) {
 579			long_hpd_pulse_mask |= BIT(pin);
 580			dev_priv->display.hotplug.long_port_mask |= BIT(port);
 581		} else {
 582			short_hpd_pulse_mask |= BIT(pin);
 583			dev_priv->display.hotplug.short_port_mask |= BIT(port);
 584		}
 585	}
 586
 587	/* Now process each pin just once */
 588	for_each_hpd_pin(pin) {
 589		bool long_hpd;
 590
 591		if (!(BIT(pin) & pin_mask))
 592			continue;
 593
 594		if (dev_priv->display.hotplug.stats[pin].state == HPD_DISABLED) {
 595			/*
 596			 * On GMCH platforms the interrupt mask bits only
 597			 * prevent irq generation, not the setting of the
 598			 * hotplug bits itself. So only WARN about unexpected
 599			 * interrupts on saner platforms.
 600			 */
 601			drm_WARN_ONCE(&dev_priv->drm, !HAS_GMCH(dev_priv),
 602				      "Received HPD interrupt on pin %d although disabled\n",
 603				      pin);
 604			continue;
 605		}
 606
 607		if (dev_priv->display.hotplug.stats[pin].state != HPD_ENABLED)
 608			continue;
 609
 610		/*
 611		 * Delegate to ->hpd_pulse() if one of the encoders for this
 612		 * pin has it, otherwise let the hotplug_work deal with this
 613		 * pin directly.
 614		 */
 615		if (((short_hpd_pulse_mask | long_hpd_pulse_mask) & BIT(pin))) {
 616			long_hpd = long_hpd_pulse_mask & BIT(pin);
 617		} else {
 618			dev_priv->display.hotplug.event_bits |= BIT(pin);
 619			long_hpd = true;
 620			queue_hp = true;
 621		}
 622
 623		if (intel_hpd_irq_storm_detect(dev_priv, pin, long_hpd)) {
 624			dev_priv->display.hotplug.event_bits &= ~BIT(pin);
 625			storm_detected = true;
 626			queue_hp = true;
 627		}
 628	}
 629
 630	/*
 631	 * Disable any IRQs that storms were detected on. Polling enablement
 632	 * happens later in our hotplug work.
 633	 */
 634	if (storm_detected)
 635		intel_hpd_irq_setup(dev_priv);
 
 636
 637	/*
 638	 * Our hotplug handler can grab modeset locks (by calling down into the
 639	 * fb helpers). Hence it must not be run on our own dev-priv->wq work
 640	 * queue for otherwise the flush_work in the pageflip code will
 641	 * deadlock.
 642	 */
 643	if (queue_dig)
 644		queue_work(dev_priv->display.hotplug.dp_wq, &dev_priv->display.hotplug.dig_port_work);
 645	if (queue_hp)
 646		queue_delayed_detection_work(dev_priv,
 647					     &dev_priv->display.hotplug.hotplug_work, 0);
 648
 649	spin_unlock(&dev_priv->irq_lock);
 650}
 651
 652/**
 653 * intel_hpd_init - initializes and enables hpd support
 654 * @dev_priv: i915 device instance
 655 *
 656 * This function enables the hotplug support. It requires that interrupts have
 657 * already been enabled with intel_irq_init_hw(). From this point on hotplug and
 658 * poll request can run concurrently to other code, so locking rules must be
 659 * obeyed.
 660 *
 661 * This is a separate step from interrupt enabling to simplify the locking rules
 662 * in the driver load and resume code.
 663 *
 664 * Also see: intel_hpd_poll_enable() and intel_hpd_poll_disable().
 665 */
 666void intel_hpd_init(struct drm_i915_private *dev_priv)
 667{
 668	int i;
 669
 670	if (!HAS_DISPLAY(dev_priv))
 671		return;
 672
 673	for_each_hpd_pin(i) {
 674		dev_priv->display.hotplug.stats[i].count = 0;
 675		dev_priv->display.hotplug.stats[i].state = HPD_ENABLED;
 676	}
 677
 678	/*
 679	 * Interrupt setup is already guaranteed to be single-threaded, this is
 680	 * just to make the assert_spin_locked checks happy.
 681	 */
 682	spin_lock_irq(&dev_priv->irq_lock);
 683	intel_hpd_irq_setup(dev_priv);
 684	spin_unlock_irq(&dev_priv->irq_lock);
 685}
 686
 687static void i915_hpd_poll_detect_connectors(struct drm_i915_private *i915)
 688{
 689	struct drm_connector_list_iter conn_iter;
 690	struct intel_connector *connector;
 691	struct intel_connector *first_changed_connector = NULL;
 692	int changed = 0;
 693
 694	mutex_lock(&i915->drm.mode_config.mutex);
 695
 696	if (!i915->drm.mode_config.poll_enabled)
 697		goto out;
 698
 699	drm_connector_list_iter_begin(&i915->drm, &conn_iter);
 700	for_each_intel_connector_iter(connector, &conn_iter) {
 701		if (!(connector->base.polled & DRM_CONNECTOR_POLL_HPD))
 702			continue;
 703
 704		if (intel_hotplug_detect_connector(connector) != INTEL_HOTPLUG_CHANGED)
 705			continue;
 706
 707		changed++;
 708
 709		if (changed == 1) {
 710			drm_connector_get(&connector->base);
 711			first_changed_connector = connector;
 712		}
 713	}
 714	drm_connector_list_iter_end(&conn_iter);
 715
 716out:
 717	mutex_unlock(&i915->drm.mode_config.mutex);
 718
 719	if (!changed)
 720		return;
 721
 722	if (changed == 1)
 723		drm_kms_helper_connector_hotplug_event(&first_changed_connector->base);
 724	else
 725		drm_kms_helper_hotplug_event(&i915->drm);
 726
 727	drm_connector_put(&first_changed_connector->base);
 728}
 729
 730static void i915_hpd_poll_init_work(struct work_struct *work)
 731{
 732	struct drm_i915_private *dev_priv =
 733		container_of(work, struct drm_i915_private,
 734			     display.hotplug.poll_init_work);
 
 735	struct drm_connector_list_iter conn_iter;
 736	struct intel_connector *connector;
 737	intel_wakeref_t wakeref;
 738	bool enabled;
 739
 740	mutex_lock(&dev_priv->drm.mode_config.mutex);
 741
 742	enabled = READ_ONCE(dev_priv->display.hotplug.poll_enabled);
 743	/*
 744	 * Prevent taking a power reference from this sequence of
 745	 * i915_hpd_poll_init_work() -> drm_helper_hpd_irq_event() ->
 746	 * connector detect which would requeue i915_hpd_poll_init_work()
 747	 * and so risk an endless loop of this same sequence.
 748	 */
 749	if (!enabled) {
 750		wakeref = intel_display_power_get(dev_priv,
 751						  POWER_DOMAIN_DISPLAY_CORE);
 752		drm_WARN_ON(&dev_priv->drm,
 753			    READ_ONCE(dev_priv->display.hotplug.poll_enabled));
 754		cancel_work(&dev_priv->display.hotplug.poll_init_work);
 755	}
 756
 757	spin_lock_irq(&dev_priv->irq_lock);
 758
 759	drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
 760	for_each_intel_connector_iter(connector, &conn_iter) {
 761		enum hpd_pin pin;
 762
 763		pin = intel_connector_hpd_pin(connector);
 764		if (pin == HPD_NONE)
 765			continue;
 766
 767		if (dev_priv->display.hotplug.stats[pin].state == HPD_DISABLED)
 768			continue;
 769
 770		connector->base.polled = connector->polled;
 771
 772		if (enabled && connector->base.polled == DRM_CONNECTOR_POLL_HPD)
 773			connector->base.polled = DRM_CONNECTOR_POLL_CONNECT |
 774				DRM_CONNECTOR_POLL_DISCONNECT;
 775	}
 776	drm_connector_list_iter_end(&conn_iter);
 777
 778	spin_unlock_irq(&dev_priv->irq_lock);
 779
 780	if (enabled)
 781		drm_kms_helper_poll_reschedule(&dev_priv->drm);
 782
 783	mutex_unlock(&dev_priv->drm.mode_config.mutex);
 784
 785	/*
 786	 * We might have missed any hotplugs that happened while we were
 787	 * in the middle of disabling polling
 788	 */
 789	if (!enabled) {
 790		i915_hpd_poll_detect_connectors(dev_priv);
 791
 792		intel_display_power_put(dev_priv,
 793					POWER_DOMAIN_DISPLAY_CORE,
 794					wakeref);
 795	}
 796}
 797
 798/**
 799 * intel_hpd_poll_enable - enable polling for connectors with hpd
 800 * @dev_priv: i915 device instance
 801 *
 802 * This function enables polling for all connectors which support HPD.
 803 * Under certain conditions HPD may not be functional. On most Intel GPUs,
 804 * this happens when we enter runtime suspend.
 805 * On Valleyview and Cherryview systems, this also happens when we shut off all
 806 * of the powerwells.
 807 *
 808 * Since this function can get called in contexts where we're already holding
 809 * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
 810 * worker.
 811 *
 812 * Also see: intel_hpd_init() and intel_hpd_poll_disable().
 813 */
 814void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
 815{
 816	if (!HAS_DISPLAY(dev_priv) ||
 817	    !intel_display_device_enabled(dev_priv))
 818		return;
 819
 820	WRITE_ONCE(dev_priv->display.hotplug.poll_enabled, true);
 821
 822	/*
 823	 * We might already be holding dev->mode_config.mutex, so do this in a
 824	 * seperate worker
 825	 * As well, there's no issue if we race here since we always reschedule
 826	 * this worker anyway
 827	 */
 828	spin_lock_irq(&dev_priv->irq_lock);
 829	queue_detection_work(dev_priv,
 830			     &dev_priv->display.hotplug.poll_init_work);
 831	spin_unlock_irq(&dev_priv->irq_lock);
 832}
 833
 834/**
 835 * intel_hpd_poll_disable - disable polling for connectors with hpd
 836 * @dev_priv: i915 device instance
 837 *
 838 * This function disables polling for all connectors which support HPD.
 839 * Under certain conditions HPD may not be functional. On most Intel GPUs,
 840 * this happens when we enter runtime suspend.
 841 * On Valleyview and Cherryview systems, this also happens when we shut off all
 842 * of the powerwells.
 843 *
 844 * Since this function can get called in contexts where we're already holding
 845 * dev->mode_config.mutex, we do the actual hotplug enabling in a seperate
 846 * worker.
 847 *
 848 * Also used during driver init to initialize connector->polled
 849 * appropriately for all connectors.
 850 *
 851 * Also see: intel_hpd_init() and intel_hpd_poll_enable().
 852 */
 853void intel_hpd_poll_disable(struct drm_i915_private *dev_priv)
 854{
 855	if (!HAS_DISPLAY(dev_priv))
 856		return;
 857
 858	WRITE_ONCE(dev_priv->display.hotplug.poll_enabled, false);
 859
 860	spin_lock_irq(&dev_priv->irq_lock);
 861	queue_detection_work(dev_priv,
 862			     &dev_priv->display.hotplug.poll_init_work);
 863	spin_unlock_irq(&dev_priv->irq_lock);
 864}
 865
 866void intel_hpd_init_early(struct drm_i915_private *i915)
 867{
 868	INIT_DELAYED_WORK(&i915->display.hotplug.hotplug_work,
 869			  i915_hotplug_work_func);
 870	INIT_WORK(&i915->display.hotplug.dig_port_work, i915_digport_work_func);
 871	INIT_WORK(&i915->display.hotplug.poll_init_work, i915_hpd_poll_init_work);
 872	INIT_DELAYED_WORK(&i915->display.hotplug.reenable_work,
 873			  intel_hpd_irq_storm_reenable_work);
 874
 875	i915->display.hotplug.hpd_storm_threshold = HPD_STORM_DEFAULT_THRESHOLD;
 876	/* If we have MST support, we want to avoid doing short HPD IRQ storm
 877	 * detection, as short HPD storms will occur as a natural part of
 878	 * sideband messaging with MST.
 879	 * On older platforms however, IRQ storms can occur with both long and
 880	 * short pulses, as seen on some G4x systems.
 881	 */
 882	i915->display.hotplug.hpd_short_storm_enabled = !HAS_DP_MST(i915);
 883}
 884
 885static bool cancel_all_detection_work(struct drm_i915_private *i915)
 886{
 887	bool was_pending = false;
 888
 889	if (cancel_delayed_work_sync(&i915->display.hotplug.hotplug_work))
 890		was_pending = true;
 891	if (cancel_work_sync(&i915->display.hotplug.poll_init_work))
 892		was_pending = true;
 893	if (cancel_delayed_work_sync(&i915->display.hotplug.reenable_work))
 894		was_pending = true;
 895
 896	return was_pending;
 897}
 898
 899void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 900{
 901	if (!HAS_DISPLAY(dev_priv))
 902		return;
 903
 904	spin_lock_irq(&dev_priv->irq_lock);
 905
 906	dev_priv->display.hotplug.long_port_mask = 0;
 907	dev_priv->display.hotplug.short_port_mask = 0;
 908	dev_priv->display.hotplug.event_bits = 0;
 909	dev_priv->display.hotplug.retry_bits = 0;
 910
 911	spin_unlock_irq(&dev_priv->irq_lock);
 912
 913	cancel_work_sync(&dev_priv->display.hotplug.dig_port_work);
 914
 915	/*
 916	 * All other work triggered by hotplug events should be canceled by
 917	 * now.
 918	 */
 919	if (cancel_all_detection_work(dev_priv))
 920		drm_dbg_kms(&dev_priv->drm, "Hotplug detection work still active\n");
 921}
 922
 923bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
 924{
 925	bool ret = false;
 926
 927	if (pin == HPD_NONE)
 928		return false;
 929
 930	spin_lock_irq(&dev_priv->irq_lock);
 931	if (dev_priv->display.hotplug.stats[pin].state == HPD_ENABLED) {
 932		dev_priv->display.hotplug.stats[pin].state = HPD_DISABLED;
 933		ret = true;
 934	}
 935	spin_unlock_irq(&dev_priv->irq_lock);
 936
 937	return ret;
 938}
 939
 940void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
 941{
 942	if (pin == HPD_NONE)
 943		return;
 944
 945	spin_lock_irq(&dev_priv->irq_lock);
 946	dev_priv->display.hotplug.stats[pin].state = HPD_ENABLED;
 947	spin_unlock_irq(&dev_priv->irq_lock);
 948}
 949
 950static void queue_work_for_missed_irqs(struct drm_i915_private *i915)
 951{
 952	bool queue_work = false;
 953	enum hpd_pin pin;
 954
 955	lockdep_assert_held(&i915->irq_lock);
 956
 957	if (i915->display.hotplug.event_bits ||
 958	    i915->display.hotplug.retry_bits)
 959		queue_work = true;
 960
 961	for_each_hpd_pin(pin) {
 962		switch (i915->display.hotplug.stats[pin].state) {
 963		case HPD_MARK_DISABLED:
 964			queue_work = true;
 965			break;
 966		case HPD_ENABLED:
 967			break;
 968		default:
 969			MISSING_CASE(i915->display.hotplug.stats[pin].state);
 970		}
 971	}
 972
 973	if (queue_work)
 974		queue_delayed_detection_work(i915, &i915->display.hotplug.hotplug_work, 0);
 975}
 976
 977void intel_hpd_enable_detection_work(struct drm_i915_private *i915)
 978{
 979	spin_lock_irq(&i915->irq_lock);
 980	i915->display.hotplug.detection_work_enabled = true;
 981	queue_work_for_missed_irqs(i915);
 982	spin_unlock_irq(&i915->irq_lock);
 983}
 984
 985void intel_hpd_disable_detection_work(struct drm_i915_private *i915)
 986{
 987	spin_lock_irq(&i915->irq_lock);
 988	i915->display.hotplug.detection_work_enabled = false;
 989	spin_unlock_irq(&i915->irq_lock);
 990
 991	cancel_all_detection_work(i915);
 992}
 993
 994bool intel_hpd_schedule_detection(struct drm_i915_private *i915)
 995{
 996	unsigned long flags;
 997	bool ret;
 998
 999	spin_lock_irqsave(&i915->irq_lock, flags);
1000	ret = queue_delayed_detection_work(i915, &i915->display.hotplug.hotplug_work, 0);
1001	spin_unlock_irqrestore(&i915->irq_lock, flags);
1002
1003	return ret;
1004}
1005
1006static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
1007{
1008	struct drm_i915_private *dev_priv = m->private;
1009	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
1010
1011	/* Synchronize with everything first in case there's been an HPD
1012	 * storm, but we haven't finished handling it in the kernel yet
1013	 */
1014	intel_synchronize_irq(dev_priv);
1015	flush_work(&dev_priv->display.hotplug.dig_port_work);
1016	flush_delayed_work(&dev_priv->display.hotplug.hotplug_work);
1017
1018	seq_printf(m, "Threshold: %d\n", hotplug->hpd_storm_threshold);
1019	seq_printf(m, "Detected: %s\n",
1020		   str_yes_no(delayed_work_pending(&hotplug->reenable_work)));
1021
1022	return 0;
1023}
1024
1025static ssize_t i915_hpd_storm_ctl_write(struct file *file,
1026					const char __user *ubuf, size_t len,
1027					loff_t *offp)
1028{
1029	struct seq_file *m = file->private_data;
1030	struct drm_i915_private *dev_priv = m->private;
1031	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
1032	unsigned int new_threshold;
1033	int i;
1034	char *newline;
1035	char tmp[16];
1036
1037	if (len >= sizeof(tmp))
1038		return -EINVAL;
1039
1040	if (copy_from_user(tmp, ubuf, len))
1041		return -EFAULT;
1042
1043	tmp[len] = '\0';
1044
1045	/* Strip newline, if any */
1046	newline = strchr(tmp, '\n');
1047	if (newline)
1048		*newline = '\0';
1049
1050	if (strcmp(tmp, "reset") == 0)
1051		new_threshold = HPD_STORM_DEFAULT_THRESHOLD;
1052	else if (kstrtouint(tmp, 10, &new_threshold) != 0)
1053		return -EINVAL;
1054
1055	if (new_threshold > 0)
1056		drm_dbg_kms(&dev_priv->drm,
1057			    "Setting HPD storm detection threshold to %d\n",
1058			    new_threshold);
1059	else
1060		drm_dbg_kms(&dev_priv->drm, "Disabling HPD storm detection\n");
1061
1062	spin_lock_irq(&dev_priv->irq_lock);
1063	hotplug->hpd_storm_threshold = new_threshold;
1064	/* Reset the HPD storm stats so we don't accidentally trigger a storm */
1065	for_each_hpd_pin(i)
1066		hotplug->stats[i].count = 0;
1067	spin_unlock_irq(&dev_priv->irq_lock);
1068
1069	/* Re-enable hpd immediately if we were in an irq storm */
1070	flush_delayed_work(&dev_priv->display.hotplug.reenable_work);
1071
1072	return len;
1073}
1074
1075static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
1076{
1077	return single_open(file, i915_hpd_storm_ctl_show, inode->i_private);
1078}
1079
1080static const struct file_operations i915_hpd_storm_ctl_fops = {
1081	.owner = THIS_MODULE,
1082	.open = i915_hpd_storm_ctl_open,
1083	.read = seq_read,
1084	.llseek = seq_lseek,
1085	.release = single_release,
1086	.write = i915_hpd_storm_ctl_write
1087};
1088
1089static int i915_hpd_short_storm_ctl_show(struct seq_file *m, void *data)
1090{
1091	struct drm_i915_private *dev_priv = m->private;
1092
1093	seq_printf(m, "Enabled: %s\n",
1094		   str_yes_no(dev_priv->display.hotplug.hpd_short_storm_enabled));
1095
1096	return 0;
1097}
1098
1099static int
1100i915_hpd_short_storm_ctl_open(struct inode *inode, struct file *file)
1101{
1102	return single_open(file, i915_hpd_short_storm_ctl_show,
1103			   inode->i_private);
1104}
1105
1106static ssize_t i915_hpd_short_storm_ctl_write(struct file *file,
1107					      const char __user *ubuf,
1108					      size_t len, loff_t *offp)
1109{
1110	struct seq_file *m = file->private_data;
1111	struct drm_i915_private *dev_priv = m->private;
1112	struct intel_hotplug *hotplug = &dev_priv->display.hotplug;
1113	char *newline;
1114	char tmp[16];
1115	int i;
1116	bool new_state;
1117
1118	if (len >= sizeof(tmp))
1119		return -EINVAL;
1120
1121	if (copy_from_user(tmp, ubuf, len))
1122		return -EFAULT;
1123
1124	tmp[len] = '\0';
1125
1126	/* Strip newline, if any */
1127	newline = strchr(tmp, '\n');
1128	if (newline)
1129		*newline = '\0';
1130
1131	/* Reset to the "default" state for this system */
1132	if (strcmp(tmp, "reset") == 0)
1133		new_state = !HAS_DP_MST(dev_priv);
1134	else if (kstrtobool(tmp, &new_state) != 0)
1135		return -EINVAL;
1136
1137	drm_dbg_kms(&dev_priv->drm, "%sabling HPD short storm detection\n",
1138		    new_state ? "En" : "Dis");
1139
1140	spin_lock_irq(&dev_priv->irq_lock);
1141	hotplug->hpd_short_storm_enabled = new_state;
1142	/* Reset the HPD storm stats so we don't accidentally trigger a storm */
1143	for_each_hpd_pin(i)
1144		hotplug->stats[i].count = 0;
1145	spin_unlock_irq(&dev_priv->irq_lock);
1146
1147	/* Re-enable hpd immediately if we were in an irq storm */
1148	flush_delayed_work(&dev_priv->display.hotplug.reenable_work);
1149
1150	return len;
1151}
1152
1153static const struct file_operations i915_hpd_short_storm_ctl_fops = {
1154	.owner = THIS_MODULE,
1155	.open = i915_hpd_short_storm_ctl_open,
1156	.read = seq_read,
1157	.llseek = seq_lseek,
1158	.release = single_release,
1159	.write = i915_hpd_short_storm_ctl_write,
1160};
1161
1162void intel_hpd_debugfs_register(struct drm_i915_private *i915)
1163{
1164	struct drm_minor *minor = i915->drm.primary;
1165
1166	debugfs_create_file("i915_hpd_storm_ctl", 0644, minor->debugfs_root,
1167			    i915, &i915_hpd_storm_ctl_fops);
1168	debugfs_create_file("i915_hpd_short_storm_ctl", 0644, minor->debugfs_root,
1169			    i915, &i915_hpd_short_storm_ctl_fops);
1170	debugfs_create_bool("i915_ignore_long_hpd", 0644, minor->debugfs_root,
1171			    &i915->display.hotplug.ignore_long_hpd);
1172}