drm/i915: Wire up port A aux channel

Useful for dp aux to work better. Also stop enabling the port A
hotplug event - eDP panels are expected to fire that interupt and
we're not really ready to deal with them. This is consistent with how
we handle port A on ilk-hsw.

The more important bit is that we must delay the enabling of hotplug
interrupts until all the encoders are fully set up. But we need irq
support earlier than that, hence hotplug interrupts can only be
enabled in the ->hpd_irq_setup callback.

v2: Drop the _HOTPLUG, it isn't (Ville).

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -1778,6 +1778,21 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 		}
 	}
 
+	if (master_ctl & GEN8_DE_PORT_IRQ) {
+		tmp = I915_READ(GEN8_DE_PORT_IIR);
+		if (tmp & GEN8_AUX_CHANNEL_A)
+			dp_aux_irq_handler(dev);
+		else if (tmp)
+			DRM_ERROR("Unexpected DE Port interrupt\n");
+		else
+			DRM_ERROR("The master control interrupt lied (DE PORT)!\n");
+
+		if (tmp) {
+			I915_WRITE(GEN8_DE_PORT_IIR, tmp);
+			ret = IRQ_HANDLED;
+		}
+	}
+
 	for_each_pipe(pipe) {
 		uint32_t pipe_iir;
 
@@ -2883,8 +2898,8 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
 	}
 	POSTING_READ(GEN8_DE_PIPE_ISR(0));
 
-	I915_WRITE(GEN8_DE_PORT_IMR, ~_PORT_DP_A_HOTPLUG);
-	I915_WRITE(GEN8_DE_PORT_IER, _PORT_DP_A_HOTPLUG);
+	I915_WRITE(GEN8_DE_PORT_IMR, ~GEN8_AUX_CHANNEL_A);
+	I915_WRITE(GEN8_DE_PORT_IER, GEN8_AUX_CHANNEL_A);
 	POSTING_READ(GEN8_DE_PORT_IER);
 }
 

drivers/gpu/drm/i915/i915_reg.h

@@ -4073,7 +4073,8 @@
 #define GEN8_DE_PORT_IMR 0x44444
 #define GEN8_DE_PORT_IIR 0x44448
 #define GEN8_DE_PORT_IER 0x4444c
-#define  _PORT_DP_A_HOTPLUG		(1 << 3)
+#define  GEN8_PORT_DP_A_HOTPLUG		(1 << 3)
+#define  GEN8_AUX_CHANNEL_A		(1 << 0)
 
 #define GEN8_DE_MISC_ISR 0x44460
 #define GEN8_DE_MISC_IMR 0x44464