[Intel-gfx] [PATCH 25/49] drm/i915/bxt: Add DDI hpd handler

[Imre Deak]

From: Shashank Sharma <shashank.sharma at intel.com>

This patch adds a hot plug interrupt handler function for BXT.
What this function typically does is:
1. Check if hot plug is enabled from hot plug control register.
2. Call hpd_irq_handler with appropriate trigger to detect a
   plug storm and schedule a bottom half.
3. Clear sticky status bits in hot plug control register..

Reviewed-by: Satheeshakrishna M <satheeshakrishna.m at intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 45 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index a51c00e..4a2f85b 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2227,6 +2227,38 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
 	return ret;
 }
 
+static void bxt_hpd_handler(struct drm_device *dev, uint32_t iir_status)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t hp_control;
+	uint32_t hp_trigger;
+
+	/* Get the status */
+	hp_trigger = iir_status & BXT_DE_PORT_HOTPLUG_MASK;
+	hp_control = I915_READ(BXT_HOTPLUG_CTL);
+
+	/* Hotplug not enabled ? */
+	if (unlikely(!(hp_control & BXT_HOTPLUG_CTL_MASK))) {
+		DRM_ERROR("Interrupt when HPD disabled\n");
+		return;
+	}
+
+	DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
+		hp_control & BXT_HOTPLUG_CTL_MASK);
+
+	/* Check for HPD storm and schedule bottom half */
+	intel_hpd_irq_handler(dev, hp_trigger, hp_control, hpd_bxt);
+
+	/*
+	 * Todo: Save the hot plug status for bottom half before
+	 * clearing the sticky status bits, else the status will be
+	 * lost.
+	 */
+
+	/* Clear sticky bits in hpd status */
+	I915_WRITE(BXT_HOTPLUG_CTL, hp_control);
+}
+
 static irqreturn_t gen8_irq_handler(int irq, void *arg)
 {
 	struct drm_device *dev = arg;
@@ -2236,6 +2268,7 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 	uint32_t tmp = 0;
 	enum pipe pipe;
 	u32 aux_mask = GEN8_AUX_CHANNEL_A;
+	bool found = false;
 
 	if (!intel_irqs_enabled(dev_priv))
 		return IRQ_NONE;
@@ -2276,9 +2309,17 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 			I915_WRITE(GEN8_DE_PORT_IIR, tmp);
 			ret = IRQ_HANDLED;
 
-			if (tmp & aux_mask)
+			if (tmp & aux_mask) {
 				dp_aux_irq_handler(dev);
-			else
+				found = true;
+			}
+
+			if (tmp & BXT_DE_PORT_HOTPLUG_MASK) {
+				bxt_hpd_handler(dev, tmp);
+				found = true;
+			}
+
+			if (!found)
 				DRM_ERROR("Unexpected DE Port interrupt\n");
 		}
 		else
-- 
2.1.0