Add support for suspending the IRQ handling on the HPD pin of a given
encoder, handling IRQs that arrived while in the suspended state after
resuming the IRQ handling. This will be used by a follow-up change,
which suspends/resumes the IRQ handling around DP link training.

This is similar to the intel_hpd_disable/enable() functionality, by also
handling encoders/ports with a pulse handler (i.e. also
suspending/resuming the short/long pulse handling) and handling the IRQs
arrived in the suspended state after the handling is resumed (vs. just
dropping such IRQs).

Signed-off-by: Imre Deak <imre.d...@intel.com>
---
 .../gpu/drm/i915/display/intel_display_core.h |   2 +
 drivers/gpu/drm/i915/display/intel_hotplug.c  | 206 +++++++++++++++---
 drivers/gpu/drm/i915/display/intel_hotplug.h  |   2 +
 3 files changed, 185 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h 
b/drivers/gpu/drm/i915/display/intel_display_core.h
index 554870d2494b3..9b338d8c9f26e 100644
--- a/drivers/gpu/drm/i915/display/intel_display_core.h
+++ b/drivers/gpu/drm/i915/display/intel_display_core.h
@@ -173,6 +173,8 @@ struct intel_hotplug {
        u32 short_port_mask;
        struct work_struct dig_port_work;
 
+       u32 suspended_port_mask;
+
        struct work_struct poll_init_work;
        bool poll_enabled;
 
diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c 
b/drivers/gpu/drm/i915/display/intel_hotplug.c
index ab8e71c4b0f86..81f2be06bc2a1 100644
--- a/drivers/gpu/drm/i915/display/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
@@ -349,19 +349,71 @@ static bool intel_encoder_has_hpd_pulse(struct 
intel_encoder *encoder)
                enc_to_dig_port(encoder)->hpd_pulse != NULL;
 }
 
+static u32 port_mask_to_hpds(struct intel_display *display, u32 port_mask)
+{
+       struct intel_encoder *encoder;
+       u32 hpds = 0;
+
+       for_each_intel_encoder(display->drm, encoder) {
+               if (BIT(encoder->port) & port_mask)
+                       hpds |= BIT(encoder->hpd_pin);
+       }
+
+       return hpds;
+}
+
+static u32 hpd_mask_to_ports(struct intel_display *display, u32 hpd_mask)
+{
+       struct intel_encoder *encoder;
+       u32 ports = 0;
+
+       for_each_intel_encoder(display->drm, encoder) {
+               if (BIT(encoder->hpd_pin) & hpd_mask)
+                       ports |= BIT(encoder->port);
+       }
+
+       return ports;
+}
+
+static u32 get_suspended_hpds(struct intel_display *display)
+{
+       struct drm_i915_private *i915 = to_i915(display->drm);
+
+       lockdep_assert_held(&i915->irq_lock);
+       return port_mask_to_hpds(display, display->hotplug.suspended_port_mask);
+}
+
+/*
+ * Get the mask of all the ports using a suspended HPD pin, accounting for
+ * ports sharing their - suspended - HPD pin with another port.
+ */
+static u32 get_suspended_hpd_ports(struct intel_display *display)
+{
+       struct drm_i915_private *i915 = to_i915(display->drm);
+
+       lockdep_assert_held(&i915->irq_lock);
+       return hpd_mask_to_ports(display, get_suspended_hpds(display));
+}
+
 static void i915_digport_work_func(struct work_struct *work)
 {
-       struct drm_i915_private *dev_priv =
-               container_of(work, struct drm_i915_private, 
display.hotplug.dig_port_work);
+       struct intel_display *display =
+               container_of(work, struct intel_display, hotplug.dig_port_work);
+       struct drm_i915_private *dev_priv = to_i915(display->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
        u32 long_port_mask, short_port_mask;
        struct intel_encoder *encoder;
+       u32 suspended_ports;
        u32 old_bits = 0;
 
        spin_lock_irq(&dev_priv->irq_lock);
-       long_port_mask = dev_priv->display.hotplug.long_port_mask;
-       dev_priv->display.hotplug.long_port_mask = 0;
-       short_port_mask = dev_priv->display.hotplug.short_port_mask;
-       dev_priv->display.hotplug.short_port_mask = 0;
+
+       suspended_ports = get_suspended_hpd_ports(display);
+       long_port_mask = hotplug->long_port_mask & ~suspended_ports;
+       hotplug->long_port_mask &= ~long_port_mask;
+       short_port_mask = hotplug->short_port_mask & ~suspended_ports;
+       hotplug->short_port_mask = ~short_port_mask;
+
        spin_unlock_irq(&dev_priv->irq_lock);
 
        for_each_intel_encoder(&dev_priv->drm, encoder) {
@@ -406,13 +458,17 @@ static void i915_digport_work_func(struct work_struct 
*work)
  */
 void intel_hpd_trigger_irq(struct intel_digital_port *dig_port)
 {
-       struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
+       struct intel_display *display = to_intel_display(dig_port);
+       struct drm_i915_private *i915 = to_i915(display->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
 
        spin_lock_irq(&i915->irq_lock);
-       i915->display.hotplug.short_port_mask |= BIT(dig_port->base.port);
-       spin_unlock_irq(&i915->irq_lock);
 
-       queue_work(i915->display.hotplug.dp_wq, 
&i915->display.hotplug.dig_port_work);
+       hotplug->short_port_mask |= BIT(dig_port->base.port);
+       if (!(BIT(dig_port->base.port) & get_suspended_hpd_ports(display)))
+               queue_work(hotplug->dp_wq, &hotplug->dig_port_work);
+
+       spin_unlock_irq(&i915->irq_lock);
 }
 
 /*
@@ -420,9 +476,10 @@ void intel_hpd_trigger_irq(struct intel_digital_port 
*dig_port)
  */
 static void i915_hotplug_work_func(struct work_struct *work)
 {
-       struct drm_i915_private *dev_priv =
-               container_of(work, struct drm_i915_private,
-                            display.hotplug.hotplug_work.work);
+       struct intel_display *display =
+               container_of(work, struct intel_display, 
hotplug.hotplug_work.work);
+       struct drm_i915_private *dev_priv = to_i915(display->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
        struct drm_connector_list_iter conn_iter;
        struct intel_connector *connector;
        u32 changed = 0, retry = 0;
@@ -430,16 +487,18 @@ static void i915_hotplug_work_func(struct work_struct 
*work)
        u32 hpd_retry_bits;
        struct drm_connector *first_changed_connector = NULL;
        int changed_connectors = 0;
+       u32 suspended_hpds;
 
        mutex_lock(&dev_priv->drm.mode_config.mutex);
        drm_dbg_kms(&dev_priv->drm, "running encoder hotplug functions\n");
 
        spin_lock_irq(&dev_priv->irq_lock);
 
-       hpd_event_bits = dev_priv->display.hotplug.event_bits;
-       dev_priv->display.hotplug.event_bits = 0;
-       hpd_retry_bits = dev_priv->display.hotplug.retry_bits;
-       dev_priv->display.hotplug.retry_bits = 0;
+       suspended_hpds = get_suspended_hpds(display);
+       hpd_event_bits = hotplug->event_bits & ~suspended_hpds;
+       hotplug->event_bits &= ~hpd_event_bits;
+       hpd_retry_bits = hotplug->retry_bits & ~suspended_hpds;
+       hotplug->retry_bits &= ~hpd_retry_bits;
 
        /* Enable polling for connectors which had HPD IRQ storms */
        intel_hpd_irq_storm_switch_to_polling(dev_priv);
@@ -538,11 +597,13 @@ static void i915_hotplug_work_func(struct work_struct 
*work)
 void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
                           u32 pin_mask, u32 long_mask)
 {
+       struct intel_display *display = to_intel_display(&dev_priv->drm);
        struct intel_encoder *encoder;
        bool storm_detected = false;
        bool queue_dig = false, queue_hp = false;
        u32 long_hpd_pulse_mask = 0;
        u32 short_hpd_pulse_mask = 0;
+       u32 suspended_hpds;
        enum hpd_pin pin;
 
        if (!pin_mask)
@@ -550,6 +611,8 @@ void intel_hpd_irq_handler(struct drm_i915_private 
*dev_priv,
 
        spin_lock(&dev_priv->irq_lock);
 
+       suspended_hpds = get_suspended_hpds(display);
+
        /*
         * Determine whether ->hpd_pulse() exists for each pin, and
         * whether we have a short or a long pulse. This is needed
@@ -573,7 +636,9 @@ void intel_hpd_irq_handler(struct drm_i915_private 
*dev_priv,
                        "digital hpd on [ENCODER:%d:%s] - %s\n",
                        encoder->base.base.id, encoder->base.name,
                        long_hpd ? "long" : "short");
-               queue_dig = true;
+
+               if (!(BIT(pin) & suspended_hpds))
+                       queue_dig = true;
 
                if (long_hpd) {
                        long_hpd_pulse_mask |= BIT(pin);
@@ -617,7 +682,9 @@ void intel_hpd_irq_handler(struct drm_i915_private 
*dev_priv,
                } else {
                        dev_priv->display.hotplug.event_bits |= BIT(pin);
                        long_hpd = true;
-                       queue_hp = true;
+
+                       if (!(BIT(pin) & suspended_hpds))
+                               queue_hp = true;
                }
 
                if (intel_hpd_irq_storm_detect(dev_priv, pin, long_hpd)) {
@@ -915,11 +982,15 @@ static bool cancel_all_detection_work(struct 
drm_i915_private *i915)
 
 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 {
+       struct intel_display *display = to_intel_display(&dev_priv->drm);
+
        if (!HAS_DISPLAY(dev_priv))
                return;
 
        spin_lock_irq(&dev_priv->irq_lock);
 
+       drm_WARN_ON(display->drm, display->hotplug.suspended_port_mask);
+
        dev_priv->display.hotplug.long_port_mask = 0;
        dev_priv->display.hotplug.short_port_mask = 0;
        dev_priv->display.hotplug.event_bits = 0;
@@ -966,19 +1037,22 @@ void intel_hpd_enable(struct drm_i915_private *dev_priv, 
enum hpd_pin pin)
 
 static void queue_work_for_missed_irqs(struct drm_i915_private *i915)
 {
-       bool queue_work = false;
+       struct intel_display *display = to_intel_display(&i915->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
+       bool queue_hp_work = false;
+       u32 suspended_hpds;
        enum hpd_pin pin;
 
        lockdep_assert_held(&i915->irq_lock);
 
-       if (i915->display.hotplug.event_bits ||
-           i915->display.hotplug.retry_bits)
-               queue_work = true;
+       suspended_hpds = get_suspended_hpds(display);
+       if ((hotplug->event_bits | hotplug->retry_bits) & ~suspended_hpds)
+               queue_hp_work = true;
 
        for_each_hpd_pin(pin) {
                switch (i915->display.hotplug.stats[pin].state) {
                case HPD_MARK_DISABLED:
-                       queue_work = true;
+                       queue_hp_work = true;
                        break;
                case HPD_DISABLED:
                case HPD_ENABLED:
@@ -988,10 +1062,92 @@ static void queue_work_for_missed_irqs(struct 
drm_i915_private *i915)
                }
        }
 
-       if (queue_work)
+       if ((hotplug->long_port_mask | hotplug->short_port_mask) &
+           ~hpd_mask_to_ports(display, suspended_hpds))
+               queue_work(hotplug->dp_wq, &hotplug->dig_port_work);
+
+       if (queue_hp_work)
                queue_delayed_detection_work(i915, 
&i915->display.hotplug.hotplug_work, 0);
 }
 
+/**
+ * intel_hpd_suspend - Suspend handling of HPD IRQs on an HPD pin
+ * @encoder: Encoder to suspend the HPD handling for
+ *
+ * Suspends the handling of HPD IRQs on the HPD pin of @encoder.
+ *
+ * On return:
+ * - It's guaranteed that the suspended encoders' HPD pulse handler
+ *   (via intel_digital_port::hpd_pulse()) is not running.
+ * - The hotplug event handling (via intel_encoder::hotplug()) of an
+ *   HPD IRQ pending at the time this function is called may be still
+ *   running.
+ * - Detection on the encoder's connector (via
+ *   drm_connector_helper_funcs::detect_ctx(),
+ *   drm_connector_funcs::detect()) remains allowed, for instance as part of
+ *   userspace connector probing, or DRM core's connector polling.
+ *
+ * A nested call of this function on the same encoder is not allowed. The call
+ * must be followed by calling intel_hpd_resume().
+ *
+ * Note that the handling of HPD IRQs for another encoder using the same HPD
+ * pin as that of @encoder will be also suspended.
+ */
+void intel_hpd_suspend(struct intel_encoder *encoder)
+{
+       struct intel_display *display = to_intel_display(encoder);
+       struct drm_i915_private *i915 = to_i915(display->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
+
+       if (encoder->hpd_pin == HPD_NONE)
+               return;
+
+       spin_lock_irq(&i915->irq_lock);
+
+       drm_WARN_ON(display->drm, BIT(encoder->port) & 
hotplug->suspended_port_mask);
+       hotplug->suspended_port_mask |= BIT(encoder->port);
+
+       spin_unlock_irq(&i915->irq_lock);
+
+       flush_work(&hotplug->dig_port_work);
+}
+
+static void resume_hpd(struct intel_encoder *encoder)
+{
+       struct intel_display *display = to_intel_display(encoder);
+       struct drm_i915_private *i915 = to_i915(display->drm);
+       struct intel_hotplug *hotplug = &display->hotplug;
+
+       lockdep_assert_held(&i915->irq_lock);
+
+       drm_WARN_ON(display->drm, !(BIT(encoder->port) & 
hotplug->suspended_port_mask));
+       hotplug->suspended_port_mask &= ~BIT(encoder->port);
+
+       queue_work_for_missed_irqs(i915);
+}
+
+/**
+ * intel_hpd_resume - Resume handling of HPD IRQs on an HPD pin
+ * @encoder: Encoder to resume the HPD handling for
+ *
+ * Resume the handling of HPD IRQs on the HPD pin of @encoder, which was
+ * previously suspended by intel_hpd_suspend(). Any HPD IRQ raised on the
+ * HPD pin while it was suspended will be handled for @encoder and for any
+ * other encoder sharing the same HPD pin.
+ */
+void intel_hpd_resume(struct intel_encoder *encoder)
+{
+       struct intel_display *display = to_intel_display(encoder);
+       struct drm_i915_private *i915 = to_i915(display->drm);
+
+       if (encoder->hpd_pin == HPD_NONE)
+               return;
+
+       spin_lock_irq(&i915->irq_lock);
+       resume_hpd(encoder);
+       spin_unlock_irq(&i915->irq_lock);
+}
+
 void intel_hpd_enable_detection_work(struct drm_i915_private *i915)
 {
        spin_lock_irq(&i915->irq_lock);
diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.h 
b/drivers/gpu/drm/i915/display/intel_hotplug.h
index d6986902b0545..5180731def7cc 100644
--- a/drivers/gpu/drm/i915/display/intel_hotplug.h
+++ b/drivers/gpu/drm/i915/display/intel_hotplug.h
@@ -28,6 +28,8 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
 enum hpd_pin intel_hpd_pin_default(enum port port);
 bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
 void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
+void intel_hpd_suspend(struct intel_encoder *encoder);
+void intel_hpd_resume(struct intel_encoder *encoder);
 void intel_hpd_debugfs_register(struct drm_i915_private *i915);
 
 void intel_hpd_enable_detection_work(struct drm_i915_private *i915);
-- 
2.44.2

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