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[PATCH v6 0/4] Fixes for HPD

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  [PATCH v6 0/4] Fixes for HPD Lyude <cpaul@redhat.com> - 2016-06-21 23:20 +0200
    [PATCH v6 3/4] drm/i915/vlv: Disable HPD in valleyview_crt_detect_hotplug() Lyude <cpaul@redhat.com> - 2016-06-21 23:20 +0200
    [PATCH v6 2/4] drm/i915/vlv: Reset the ADPA in vlv_display_power_well_init() Lyude <cpaul@redhat.com> - 2016-06-21 23:30 +0200

#1428178 — [PATCH v6 0/4] Fixes for HPD

Latest version of:

https://lists.freedesktop.org/archives/intel-gfx/2016-June/098787.html

The only patch that's changed here is 4/4, the rest are just being sent so that
they can be in one thread to make things easier for reviewers

Lyude (4):
  drm/i915/vlv: Make intel_crt_reset() per-encoder
  drm/i915/vlv: Reset the ADPA in vlv_display_power_well_init()
  drm/i915/vlv: Disable HPD in valleyview_crt_detect_hotplug()
  drm/i915: Enable polling when we don't have hpd

 drivers/gpu/drm/i915/i915_drv.c         |   3 +
 drivers/gpu/drm/i915/i915_drv.h         |   5 ++
 drivers/gpu/drm/i915/intel_crt.c        |  28 ++++++--
 drivers/gpu/drm/i915/intel_drv.h        |   4 +-
 drivers/gpu/drm/i915/intel_hotplug.c    | 117 ++++++++++++++++++++++++++++----
 drivers/gpu/drm/i915/intel_runtime_pm.c |   9 +++
 6 files changed, 148 insertions(+), 18 deletions(-)

-- 
2.5.5

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#1428179 — [PATCH v6 3/4] drm/i915/vlv: Disable HPD in valleyview_crt_detect_hotplug()

One of the things preventing us from using polling is the fact that
calling valleyview_crt_detect_hotplug() when there's a VGA cable
connected results in sending another hotplug. With polling enabled when
HPD is disabled, this results in a scenario like this:

- We enable power wells and reset the ADPA
- output_poll_exec does force probe on VGA, triggering a hpd
- HPD handler waits for poll to unlock dev->mode_config.mutex
- output_poll_exec shuts off the ADPA, unlocks dev->mode_config.mutex
- HPD handler runs, resets ADPA and brings us back to the start

This results in an endless irq storm getting sent from the ADPA
whenever a VGA connector gets detected in the middle of polling.

Somewhat based off of the "drm/i915: Disable CRT HPD around force
trigger" patch Ville Syrjälä sent a while back

Cc: stable@vger.kernel.org
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Lyude <cpaul@redhat.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |  2 ++
 drivers/gpu/drm/i915/intel_crt.c     | 18 ++++++++++++++++++
 drivers/gpu/drm/i915/intel_hotplug.c | 27 +++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a988a95..239a3ec 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2933,6 +2933,8 @@ void intel_hpd_init(struct drm_i915_private *dev_priv);
 void intel_hpd_init_work(struct drm_i915_private *dev_priv);
 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
 bool intel_hpd_pin_to_port(enum hpd_pin pin, 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);
 
 /* i915_irq.c */
 void i915_queue_hangcheck(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 220be7a..a626793 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -327,10 +327,25 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
 	struct drm_device *dev = connector->dev;
 	struct intel_crt *crt = intel_attached_crt(connector);
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	bool reenable_hpd;
 	u32 adpa;
 	bool ret;
 	u32 save_adpa;
 
+	/*
+	 * Doing a force trigger causes a hpd interrupt to get sent, which can
+	 * get us stuck in a loop if we're polling:
+	 *  - We enable power wells and reset the ADPA
+	 *  - output_poll_exec does force probe on VGA, triggering a hpd
+	 *  - HPD handler waits for poll to unlock dev->mode_config.mutex
+	 *  - output_poll_exec shuts off the ADPA, unlocks
+	 *    dev->mode_config.mutex
+	 *  - HPD handler runs, resets ADPA and brings us back to the start
+	 *
+	 * Just disable HPD interrupts here to prevent this
+	 */
+	reenable_hpd = intel_hpd_disable(dev_priv, crt->base.hpd_pin);
+
 	save_adpa = adpa = I915_READ(crt->adpa_reg);
 	DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);
 
@@ -353,6 +368,9 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
 
 	DRM_DEBUG_KMS("valleyview hotplug adpa=0x%x, result %d\n", adpa, ret);
 
+	if (reenable_hpd)
+		intel_hpd_enable(dev_priv, crt->base.hpd_pin);
+
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index 38eeca7..ec3285f 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -510,3 +510,30 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 	cancel_work_sync(&dev_priv->hotplug.hotplug_work);
 	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
 }
+
+bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
+{
+	bool ret = false;
+
+	if (pin == HPD_NONE)
+		return false;
+
+	spin_lock_irq(&dev_priv->irq_lock);
+	if (dev_priv->hotplug.stats[pin].state == HPD_ENABLED) {
+		dev_priv->hotplug.stats[pin].state = HPD_DISABLED;
+		ret = true;
+	}
+	spin_unlock_irq(&dev_priv->irq_lock);
+
+	return ret;
+}
+
+void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
+{
+	if (pin == HPD_NONE)
+		return;
+
+	spin_lock_irq(&dev_priv->irq_lock);
+	dev_priv->hotplug.stats[pin].state = HPD_ENABLED;
+	spin_unlock_irq(&dev_priv->irq_lock);
+}
-- 
2.5.5

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#1428188 — [PATCH v6 2/4] drm/i915/vlv: Reset the ADPA in vlv_display_power_well_init()

While VGA hotplugging worked(ish) before, it looks like that was mainly
because we'd unintentionally enable it in
valleyview_crt_detect_hotplug() when we did a force trigger. This
doesn't work reliably enough because whenever the display powerwell on
vlv gets disabled, the values set in VLV_ADPA get cleared and
consequently VGA hotplugging gets disabled. This causes bugs such as one
we found on an Intel NUC, where doing the following sequence of
hotplugs:

      - Disconnect all monitors
      - Connect VGA
      - Disconnect VGA
      - Connect HDMI

Would result in VGA hotplugging becoming disabled, due to the powerwells
getting toggled in the process of connecting HDMI.

Changes since v3:
 - Expose intel_crt_reset() through intel_drv.h and call that in
   vlv_display_power_well_init() instead of
   encoder->base.funcs->reset(&encoder->base);

Changes since v2:
 - Use intel_encoder structs instead of drm_encoder structs

Changes since v1:
 - Instead of handling the register writes ourself, we just reuse
   intel_crt_detect()
 - Instead of resetting the ADPA during display IRQ installation, we now
   reset them in vlv_display_power_well_init()

Cc: stable@vger.kernel.org
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Lyude <cpaul@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_crt.c        | 2 +-
 drivers/gpu/drm/i915/intel_drv.h        | 2 +-
 drivers/gpu/drm/i915/intel_runtime_pm.c | 7 +++++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index dfcd718..220be7a 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -713,7 +713,7 @@ static int intel_crt_set_property(struct drm_connector *connector,
 	return 0;
 }
 
-static void intel_crt_reset(struct drm_encoder *encoder)
+void intel_crt_reset(struct drm_encoder *encoder)
 {
 	struct drm_device *dev = encoder->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 496c962..dcbfdde 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1075,7 +1075,7 @@ void gen8_irq_power_well_pre_disable(struct drm_i915_private *dev_priv,
 
 /* intel_crt.c */
 void intel_crt_init(struct drm_device *dev);
-
+void intel_crt_reset(struct drm_encoder *encoder);
 
 /* intel_ddi.c */
 void intel_ddi_clk_select(struct intel_encoder *encoder,
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index e856d49..f88ef76 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -1065,6 +1065,7 @@ static void vlv_init_display_clock_gating(struct drm_i915_private *dev_priv)
 
 static void vlv_display_power_well_init(struct drm_i915_private *dev_priv)
 {
+	struct intel_encoder *encoder;
 	enum pipe pipe;
 
 	/*
@@ -1100,6 +1101,12 @@ static void vlv_display_power_well_init(struct drm_i915_private *dev_priv)
 
 	intel_hpd_init(dev_priv);
 
+	/* Re-enable the ADPA, if we have one */
+	for_each_intel_encoder(dev_priv->dev, encoder) {
+		if (encoder->type == INTEL_OUTPUT_ANALOG)
+			intel_crt_reset(&encoder->base);
+	}
+
 	i915_redisable_vga_power_on(dev_priv->dev);
 }
 
-- 
2.5.5

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