[PATCH] drm/i915: only enable sdvo hotplug irq if needed

[Jani Nikula <jani.nikula@intel.com>]

Avoid constant wakeups caused by noisy irq lines when we don't even care
about the irq. This should be particularly useful for i945g/gm where the
hotplug has been disabled:

commit 768b107e4b3be0acf6f58e914afe4f337c00932b
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri May 4 11:29:56 2012 +0200

    drm/i915: disable sdvo hotplug on i945g/gm

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=38442
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

---

N.B. This really needs a Tested-by from the bug reporter.
---
 drivers/gpu/drm/i915/intel_sdvo.c |   32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index f3762f8..14379b5 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2529,7 +2529,6 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_encoder *intel_encoder;
 	struct intel_sdvo *intel_sdvo;
-	u32 hotplug_mask;
 	int i;
 
 	intel_sdvo = kzalloc(sizeof(struct intel_sdvo), GFP_KERNEL);
@@ -2561,19 +2560,6 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 		}
 	}
 
-	hotplug_mask = 0;
-	if (IS_G4X(dev)) {
-		hotplug_mask = intel_sdvo->is_sdvob ?
-			SDVOB_HOTPLUG_INT_STATUS_G4X : SDVOC_HOTPLUG_INT_STATUS_G4X;
-	} else if (IS_GEN4(dev)) {
-		hotplug_mask = intel_sdvo->is_sdvob ?
-			SDVOB_HOTPLUG_INT_STATUS_I965 : SDVOC_HOTPLUG_INT_STATUS_I965;
-	} else {
-		hotplug_mask = intel_sdvo->is_sdvob ?
-			SDVOB_HOTPLUG_INT_STATUS_I915 : SDVOC_HOTPLUG_INT_STATUS_I915;
-	}
-	dev_priv->hotplug_supported_mask |= hotplug_mask;
-
 	drm_encoder_helper_add(&intel_encoder->base, &intel_sdvo_helper_funcs);
 
 	/* In default case sdvo lvds is false */
@@ -2595,6 +2581,24 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 		goto err;
 	}
 
+	/* Only enable the hotplug irq if we need it, to work around noisy
+	 * hotplug lines.
+	 */
+	if (intel_sdvo->hotplug_active[0] & 0x3) {
+		u32 hotplug_mask;
+		if (IS_G4X(dev)) {
+			hotplug_mask = intel_sdvo->is_sdvob ?
+				SDVOB_HOTPLUG_INT_STATUS_G4X : SDVOC_HOTPLUG_INT_STATUS_G4X;
+		} else if (IS_GEN4(dev)) {
+			hotplug_mask = intel_sdvo->is_sdvob ?
+				SDVOB_HOTPLUG_INT_STATUS_I965 : SDVOC_HOTPLUG_INT_STATUS_I965;
+		} else {
+			hotplug_mask = intel_sdvo->is_sdvob ?
+				SDVOB_HOTPLUG_INT_STATUS_I915 : SDVOC_HOTPLUG_INT_STATUS_I915;
+		}
+		dev_priv->hotplug_supported_mask |= hotplug_mask;
+	}
+
 	intel_sdvo_select_ddc_bus(dev_priv, intel_sdvo, sdvo_reg);
 
 	/* Set the input timing to the screen. Assume always input 0. */
-- 
1.7.9.5