drm/i915: extract AUX mask assignment to separate function

No change in behavior, this only allows to more easily follow the flow
of gen8_de_irq_handler without the mask assignments for each platform.
This also re-organizes the branches a little bit, so the one-off case
for CNL_WITH_PORT_F is separate from the generic gen >= 11.

v2: rename de_port_iir_aux_mask -> gen8_de_port_aux_mask (Ville)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jose Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226004900.26047-1-lucas.demarchi@intel.com

drivers/gpu/drm/i915/i915_irq.c

@@ -2676,6 +2676,25 @@ static void gen11_hpd_irq_handler(struct drm_i915_private *dev_priv, u32 iir)
 		DRM_ERROR("Unexpected DE HPD interrupt 0x%08x\n", iir);
 }
 
+static u32 gen8_de_port_aux_mask(struct drm_i915_private *dev_priv)
+{
+	u32 mask = GEN8_AUX_CHANNEL_A;
+
+	if (INTEL_GEN(dev_priv) >= 9)
+		mask |= GEN9_AUX_CHANNEL_B |
+			GEN9_AUX_CHANNEL_C |
+			GEN9_AUX_CHANNEL_D;
+
+	if (IS_CNL_WITH_PORT_F(dev_priv))
+		mask |= CNL_AUX_CHANNEL_F;
+
+	if (INTEL_GEN(dev_priv) >= 11)
+		mask |= ICL_AUX_CHANNEL_E |
+			CNL_AUX_CHANNEL_F;
+
+	return mask;
+}
+
 static irqreturn_t
 gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
 {
@@ -2731,20 +2750,7 @@ gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
 			I915_WRITE(GEN8_DE_PORT_IIR, iir);
 			ret = IRQ_HANDLED;
 
-			tmp_mask = GEN8_AUX_CHANNEL_A;
-			if (INTEL_GEN(dev_priv) >= 9)
-				tmp_mask |= GEN9_AUX_CHANNEL_B |
-					    GEN9_AUX_CHANNEL_C |
-					    GEN9_AUX_CHANNEL_D;
-
-			if (INTEL_GEN(dev_priv) >= 11)
-				tmp_mask |= ICL_AUX_CHANNEL_E;
-
-			if (IS_CNL_WITH_PORT_F(dev_priv) ||
-			    INTEL_GEN(dev_priv) >= 11)
-				tmp_mask |= CNL_AUX_CHANNEL_F;
-
-			if (iir & tmp_mask) {
+			if (iir & gen8_de_port_aux_mask(dev_priv)) {
 				dp_aux_irq_handler(dev_priv);
 				found = true;
 			}