[PATCH] drm/i915: enable sdvo interrupt on pch platforms

[Daniel Vetter <daniel.vetter@ffwll.ch>]

Noticed while strolling through docs. Might make a few dual-link dvi
users happy(ier).

v2: Remove the unrelated debug hacks in intel_display.c

v3: Preserve register contexts to not upset fastboot or the modeset
hw state checker.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_reg.h   |  2 +-
 drivers/gpu/drm/i915/intel_sdvo.c | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f2a5ea6..a981ff5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1673,7 +1673,7 @@
 #define   SDVO_ENABLE		(1 << 31)
 #define   SDVO_PIPE_B_SELECT	(1 << 30)
 #define   SDVO_STALL_SELECT	(1 << 29)
-#define   SDVO_INTERRUPT_ENABLE	(1 << 26)
+#define   SDVO_INTERRUPT_ENABLE_PCH	(1 << 23)
 /**
  * 915G/GM SDVO pixel multiplier.
  *
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index c275bf0..2c1543b 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1085,6 +1085,9 @@ static void intel_sdvo_mode_set(struct drm_encoder *encoder,
 	if (!mode)
 		return;
 
+	/* Preserve the PCH interrupt enable bit. */
+	sdvox = I915_READ(intel_sdvo->sdvo_reg) & SDVO_INTERRUPT_ENABLE_PCH;
+
 	/* First, set the input mapping for the first input to our controlled
 	 * output. This is only correct if we're a single-input device, in
 	 * which case the first input is the output from the appropriate SDVO
@@ -2775,9 +2778,18 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 	/* Only enable the hotplug irq if we need it, to work around noisy
 	 * hotplug lines.
 	 */
-	if (intel_sdvo->hotplug_active)
+	if (intel_sdvo->hotplug_active) {
 		dev_priv->hotplug_supported_mask |= hotplug_mask;
 
+		if (HAS_PCH_SPLIT(dev)) {
+			u32 temp;
+
+			temp = I915_READ(intel_sdvo->sdvo_reg);
+			temp &= SDVO_INTERRUPT_ENABLE_PCH;
+			intel_sdvo_write_sdvox(intel_sdvo, temp);
+		}
+	}
+
 	intel_sdvo_select_ddc_bus(dev_priv, intel_sdvo, sdvo_reg);
 
 	/* Set the input timing to the screen. Assume always input 0. */
-- 
1.7.11.7