drm/i915: Sync crt hotplug detection with intel video driver

This covers:
Use long crt hotplug activation time on GM45.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_reg.h

@@ -633,6 +633,22 @@
 #define   TV_HOTPLUG_INT_EN			(1 << 18)
 #define   CRT_HOTPLUG_INT_EN			(1 << 9)
 #define   CRT_HOTPLUG_FORCE_DETECT		(1 << 3)
+#define CRT_HOTPLUG_ACTIVATION_PERIOD_32	(0 << 8)
+/* must use period 64 on GM45 according to docs */
+#define CRT_HOTPLUG_ACTIVATION_PERIOD_64	(1 << 8)
+#define CRT_HOTPLUG_DAC_ON_TIME_2M		(0 << 7)
+#define CRT_HOTPLUG_DAC_ON_TIME_4M		(1 << 7)
+#define CRT_HOTPLUG_VOLTAGE_COMPARE_40		(0 << 5)
+#define CRT_HOTPLUG_VOLTAGE_COMPARE_50		(1 << 5)
+#define CRT_HOTPLUG_VOLTAGE_COMPARE_60		(2 << 5)
+#define CRT_HOTPLUG_VOLTAGE_COMPARE_70		(3 << 5)
+#define CRT_HOTPLUG_VOLTAGE_COMPARE_MASK	(3 << 5)
+#define CRT_HOTPLUG_DETECT_DELAY_1G		(0 << 4)
+#define CRT_HOTPLUG_DETECT_DELAY_2G		(1 << 4)
+#define CRT_HOTPLUG_DETECT_VOLTAGE_325MV	(0 << 2)
+#define CRT_HOTPLUG_DETECT_VOLTAGE_475MV	(1 << 2)
+#define CRT_HOTPLUG_MASK			(0x3fc) /* Bits 9-2 */
+
 
 #define PORT_HOTPLUG_STAT	0x61114
 #define   HDMIB_HOTPLUG_INT_STATUS		(1 << 29)

drivers/gpu/drm/i915/intel_crt.c

@@ -146,20 +146,39 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 temp;
+	u32 hotplug_en;
+	int i, tries = 0;
+	/*
+	 * On 4 series desktop, CRT detect sequence need to be done twice
+	 * to get a reliable result.
+	 */
 
-	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+	if (IS_G4X(dev) && !IS_GM45(dev))
+		tries = 2;
+	else
+		tries = 1;
+	hotplug_en = I915_READ(PORT_HOTPLUG_EN);
+	hotplug_en &= ~(CRT_HOTPLUG_MASK);
+	hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
 
-	temp = I915_READ(PORT_HOTPLUG_EN);
+	if (IS_GM45(dev))
+		hotplug_en |= CRT_HOTPLUG_ACTIVATION_PERIOD_64;
 
-	I915_WRITE(PORT_HOTPLUG_EN,
-		   temp | CRT_HOTPLUG_FORCE_DETECT | (1 << 5));
+	hotplug_en |= CRT_HOTPLUG_VOLTAGE_COMPARE_50;
 
-	do {
-		if (!(I915_READ(PORT_HOTPLUG_EN) & CRT_HOTPLUG_FORCE_DETECT))
-			break;
-		msleep(1);
-	} while (time_after(timeout, jiffies));
+	for (i = 0; i < tries ; i++) {
+		unsigned long timeout;
+		/* turn on the FORCE_DETECT */
+		I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
+		timeout = jiffies + msecs_to_jiffies(1000);
+		/* wait for FORCE_DETECT to go off */
+		do {
+			if (!(I915_READ(PORT_HOTPLUG_EN) &
+					CRT_HOTPLUG_FORCE_DETECT))
+				break;
+			msleep(1);
+		} while (time_after(timeout, jiffies));
+	}
 
 	if ((I915_READ(PORT_HOTPLUG_STAT) & CRT_HOTPLUG_MONITOR_MASK) ==
 	    CRT_HOTPLUG_MONITOR_COLOR)