drm/i915: don't use HPD_PORT_A as an alias for HPD_NONE

Currently HPD_PORT_A is used as an alias for HPD_NONE to mean that the
given port doesn't support long/short HPD pulse detection. SDVO and CRT
ports are like this and for these ports we only want to know whether an
hot plug event was detected on the corresponding pin. Since at least on
BXT we need long/short pulse detection on PORT A as well (added by the
next patch) remove this aliasing of HPD_PORT_A/HPD_NONE and let the
return value of intel_hpd_pin_to_port() show whether long/short pulse
detection is supported on the passed in pin.

No functional change.

v2:
- rebase on top of -nightly (Daniel)
- make the check for intel_hpd_pin_to_port() return value more readable
  (Sivakumar)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -206,11 +206,11 @@ enum intel_display_power_domain {
 
 enum hpd_pin {
 	HPD_NONE = 0,
-	HPD_PORT_A = HPD_NONE, /* PORT_A is internal */
 	HPD_TV = HPD_NONE,     /* TV is known to be unreliable */
 	HPD_CRT,
 	HPD_SDVO_B,
 	HPD_SDVO_C,
+	HPD_PORT_A,
 	HPD_PORT_B,
 	HPD_PORT_C,
 	HPD_PORT_D,
@@ -2648,7 +2648,7 @@ void intel_hpd_irq_handler(struct drm_device *dev, u32 pin_mask, u32 long_mask);
 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);
-enum port intel_hpd_pin_to_port(enum hpd_pin pin);
+bool intel_hpd_pin_to_port(enum hpd_pin pin, enum port *port);
 
 /* i915_irq.c */
 void i915_queue_hangcheck(struct drm_device *dev);

drivers/gpu/drm/i915/i915_irq.c

@@ -1273,7 +1273,9 @@ static void intel_get_hpd_pins(u32 *pin_mask, u32 *long_mask,
 
 		*pin_mask |= BIT(i);
 
-		port = intel_hpd_pin_to_port(i);
+		if (!intel_hpd_pin_to_port(i, &port))
+			continue;
+
 		if (long_pulse_detect(port, dig_hotplug_reg))
 			*long_mask |= BIT(i);
 	}

drivers/gpu/drm/i915/intel_hotplug.c

@@ -76,17 +76,23 @@
  * it will use i915_hotplug_work_func where this logic is handled.
  */
 
-enum port intel_hpd_pin_to_port(enum hpd_pin pin)
+bool intel_hpd_pin_to_port(enum hpd_pin pin, enum port *port)
 {
 	switch (pin) {
+	case HPD_PORT_A:
+		*port = PORT_A;
+		return true;
 	case HPD_PORT_B:
-		return PORT_B;
+		*port = PORT_B;
+		return true;
 	case HPD_PORT_C:
-		return PORT_C;
+		*port = PORT_C;
+		return true;
 	case HPD_PORT_D:
-		return PORT_D;
+		*port = PORT_D;
+		return true;
 	default:
-		return PORT_A; /* no hpd */
+		return false;	/* no hpd */
 	}
 }
 
@@ -369,8 +375,8 @@ void intel_hpd_irq_handler(struct drm_device *dev,
 		if (!(BIT(i) & pin_mask))
 			continue;
 
-		port = intel_hpd_pin_to_port(i);
-		is_dig_port = port && dev_priv->hotplug.irq_port[port];
+		is_dig_port = intel_hpd_pin_to_port(i, &port) &&
+			      dev_priv->hotplug.irq_port[port];
 
 		if (is_dig_port) {
 			bool long_hpd = long_mask & BIT(i);