drm/i915: dp aux irq support for g4x/vlv

Now we have this everywhere. Next up would be to wire up the DP
hotplug pin to speed up panel power sequencing for eDP panels ...

I've decided to leave the has_aux_irq logic in the code, it should
come handy for hw bringup.

For testing/fail-safety the dp aux code already has a timeout when
waiting for interrupts to signal completion and screams rather loud if
they don't arrive in time. Given that we need a real piece of hw to
talk to anyway this is probably as good as it gets.

v2: Don't check the dp aux channel bits on i965 machines, they have a
different meaning there. Yay for reusing bits at will! Spotted by
Jani.

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -1472,6 +1472,9 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
 
 			intel_hpd_irq_handler(dev, hotplug_trigger, hpd_status_i915);
 
+			if (hotplug_status & DP_AUX_CHANNEL_MASK_INT_STATUS_G4X)
+				dp_aux_irq_handler(dev);
+
 			I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
 			I915_READ(PORT_HOTPLUG_STAT);
 		}
@@ -3653,6 +3656,10 @@ static irqreturn_t i965_irq_handler(int irq, void *arg)
 			intel_hpd_irq_handler(dev, hotplug_trigger,
 					      IS_G4X(dev) ? hpd_status_gen4 : hpd_status_i915);
 
+			if (IS_G4X(dev) &&
+			    (hotplug_status & DP_AUX_CHANNEL_MASK_INT_STATUS_G4X))
+				dp_aux_irq_handler(dev);
+
 			I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
 			I915_READ(PORT_HOTPLUG_STAT);
 		}

drivers/gpu/drm/i915/i915_reg.h

@@ -2131,6 +2131,10 @@
 #define   CRT_HOTPLUG_MONITOR_COLOR		(3 << 8)
 #define   CRT_HOTPLUG_MONITOR_MONO		(2 << 8)
 #define   CRT_HOTPLUG_MONITOR_NONE		(0 << 8)
+#define   DP_AUX_CHANNEL_D_INT_STATUS_G4X	(1 << 6)
+#define   DP_AUX_CHANNEL_C_INT_STATUS_G4X	(1 << 5)
+#define   DP_AUX_CHANNEL_B_INT_STATUS_G4X	(1 << 4)
+#define   DP_AUX_CHANNEL_MASK_INT_STATUS_G4X	(1 << 4)
 /* SDVO is different across gen3/4 */
 #define   SDVOC_HOTPLUG_INT_STATUS_G4X		(1 << 3)
 #define   SDVOB_HOTPLUG_INT_STATUS_G4X		(1 << 2)

drivers/gpu/drm/i915/intel_dp.c

@@ -404,7 +404,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 	int i, ret, recv_bytes;
 	uint32_t status;
 	int try, precharge, clock = 0;
-	bool has_aux_irq = INTEL_INFO(dev)->gen >= 5 && !IS_VALLEYVIEW(dev);
+	bool has_aux_irq = true;
 	uint32_t timeout;
 
 	/* dp aux is extremely sensitive to irq latency, hence request the