[Intel-gfx] [PATCH] i915: disable DAC on Ironlake also when doing CRT load detection.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

Like on Sandybridge, disabling the DAC here when doing CRT load detect
avoids forever hangs waiting on the hardware.

test procedure on HP 2740p:
boot with no VGA plugged in, start X,
plug in VGA monitor (1280x1024)
chvt 3
machine hangs waiting forever.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 drivers/gpu/drm/i915/intel_crt.c |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index ee0732b..2a3b59b 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -160,19 +160,20 @@ static bool intel_ironlake_crt_detect_hotplug(struct drm_connector *connector)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 adpa, temp;
 	bool ret;
+	bool turn_off_dac = false;
 
 	temp = adpa = I915_READ(PCH_ADPA);
 
-	if (HAS_PCH_CPT(dev)) {
-		/* Disable DAC before force detect */
-		I915_WRITE(PCH_ADPA, adpa & ~ADPA_DAC_ENABLE);
-		(void)I915_READ(PCH_ADPA);
-	} else {
-		adpa &= ~ADPA_CRT_HOTPLUG_MASK;
-		/* disable HPD first */
-		I915_WRITE(PCH_ADPA, adpa);
-		(void)I915_READ(PCH_ADPA);
-	}
+	if (HAS_PCH_SPLIT(dev))
+		turn_off_dac = true;
+
+	adpa &= ~ADPA_CRT_HOTPLUG_MASK;
+	if (turn_off_dac)
+		adpa &= ~ADPA_DAC_ENABLE;
+
+	/* disable HPD first */
+	I915_WRITE(PCH_ADPA, adpa);
+	(void)I915_READ(PCH_ADPA);
 
 	adpa |= (ADPA_CRT_HOTPLUG_PERIOD_128 |
 			ADPA_CRT_HOTPLUG_WARMUP_10MS |
@@ -188,7 +189,7 @@ static bool intel_ironlake_crt_detect_hotplug(struct drm_connector *connector)
 	while ((I915_READ(PCH_ADPA) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) != 0)
 		;
 
-	if (HAS_PCH_CPT(dev)) {
+	if (turn_off_dac) {
 		I915_WRITE(PCH_ADPA, temp);
 		(void)I915_READ(PCH_ADPA);
 	}
-- 
1.7.1