drm/i915: Enable SDVO hotplug interrupts for HDMI and DVI

I was seeing a nasty 5 frame glitch every 10 seconds, caused by the
poll for connection on DVI attached by SDVO.

As my SDVO DVI supports hotplug detect interrupts, the fix is to
enable them, and hook them in to the various bits of driver
infrastructure so that they work reliably.

Note that this is only tested on single-function DVI-D SDVOs, on two
platforms (965GME and 945GSE), and has not been checked against a
specification document.

With lots of help from Adam Jackson <ajax@redhat.com> on IRC.

Signed-off-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_drv.h

@@ -337,9 +337,6 @@ extern void intel_release_load_detect_pipe(struct intel_encoder *intel_encoder,
 					   struct drm_connector *connector,
 					   struct intel_load_detect_pipe *old);
 
-extern struct drm_connector* intel_sdvo_find(struct drm_device *dev, int sdvoB);
-extern int intel_sdvo_supports_hotplug(struct drm_connector *connector);
-extern void intel_sdvo_set_hotplug(struct drm_connector *connector, int enable);
 extern void intelfb_restore(void);
 extern void intel_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
 				    u16 blue, int regno);

drivers/gpu/drm/i915/intel_sdvo.c

@@ -92,6 +92,11 @@ struct intel_sdvo {
 	*/
 	uint16_t attached_output;
 
+	/*
+	 * Hotplug activation bits for this device
+	 */
+	uint8_t hotplug_active[2];
+
 	/**
 	 * This is used to select the color range of RBG outputs in HDMI mode.
 	 * It is only valid when using TMDS encoding and 8 bit per color mode.
@@ -1208,74 +1213,20 @@ static bool intel_sdvo_get_capabilities(struct intel_sdvo *intel_sdvo, struct in
 	return true;
 }
 
-/* No use! */
-#if 0
-struct drm_connector* intel_sdvo_find(struct drm_device *dev, int sdvoB)
-{
-	struct drm_connector *connector = NULL;
-	struct intel_sdvo *iout = NULL;
-	struct intel_sdvo *sdvo;
-
-	/* find the sdvo connector */
-	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-		iout = to_intel_sdvo(connector);
-
-		if (iout->type != INTEL_OUTPUT_SDVO)
-			continue;
-
-		sdvo = iout->dev_priv;
-
-		if (sdvo->sdvo_reg == SDVOB && sdvoB)
-			return connector;
-
-		if (sdvo->sdvo_reg == SDVOC && !sdvoB)
-			return connector;
-
-	}
-
-	return NULL;
-}
-
-int intel_sdvo_supports_hotplug(struct drm_connector *connector)
+static int intel_sdvo_supports_hotplug(struct intel_sdvo *intel_sdvo)
 {
 	u8 response[2];
-	u8 status;
-	struct intel_sdvo *intel_sdvo;
-	DRM_DEBUG_KMS("\n");
-
-	if (!connector)
-		return 0;
-
-	intel_sdvo = to_intel_sdvo(connector);
 
 	return intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_HOT_PLUG_SUPPORT,
 				    &response, 2) && response[0];
 }
 
-void intel_sdvo_set_hotplug(struct drm_connector *connector, int on)
+static void intel_sdvo_enable_hotplug(struct intel_encoder *encoder)
 {
-	u8 response[2];
-	u8 status;
-	struct intel_sdvo *intel_sdvo = to_intel_sdvo(connector);
-
-	intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_GET_ACTIVE_HOT_PLUG, NULL, 0);
-	intel_sdvo_read_response(intel_sdvo, &response, 2);
-
-	if (on) {
-		intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_GET_HOT_PLUG_SUPPORT, NULL, 0);
-		status = intel_sdvo_read_response(intel_sdvo, &response, 2);
-
-		intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_SET_ACTIVE_HOT_PLUG, &response, 2);
-	} else {
-		response[0] = 0;
-		response[1] = 0;
-		intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_SET_ACTIVE_HOT_PLUG, &response, 2);
-	}
+	struct intel_sdvo *intel_sdvo = to_intel_sdvo(&encoder->base);
 
-	intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_GET_ACTIVE_HOT_PLUG, NULL, 0);
-	intel_sdvo_read_response(intel_sdvo, &response, 2);
+	intel_sdvo_write_cmd(intel_sdvo, SDVO_CMD_SET_ACTIVE_HOT_PLUG, &intel_sdvo->hotplug_active, 2);
 }
-#endif
 
 static bool
 intel_sdvo_multifunc_encoder(struct intel_sdvo *intel_sdvo)
@@ -2045,6 +1996,7 @@ intel_sdvo_dvi_init(struct intel_sdvo *intel_sdvo, int device)
 {
 	struct drm_encoder *encoder = &intel_sdvo->base.base;
 	struct drm_connector *connector;
+	struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
 	struct intel_connector *intel_connector;
 	struct intel_sdvo_connector *intel_sdvo_connector;
 
@@ -2062,7 +2014,17 @@ intel_sdvo_dvi_init(struct intel_sdvo *intel_sdvo, int device)
 
 	intel_connector = &intel_sdvo_connector->base;
 	connector = &intel_connector->base;
-	connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
+	if (intel_sdvo_supports_hotplug(intel_sdvo) & (1 << device)) {
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+		intel_sdvo->hotplug_active[0] |= 1 << device;
+		/* Some SDVO devices have one-shot hotplug interrupts.
+		 * Ensure that they get re-enabled when an interrupt happens.
+		 */
+		intel_encoder->hot_plug = intel_sdvo_enable_hotplug;
+		intel_sdvo_enable_hotplug(intel_encoder);
+	}
+	else
+		connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
 	encoder->encoder_type = DRM_MODE_ENCODER_TMDS;
 	connector->connector_type = DRM_MODE_CONNECTOR_DVID;
 
@@ -2569,6 +2531,14 @@ bool intel_sdvo_init(struct drm_device *dev, int sdvo_reg)
 	if (!intel_sdvo_get_capabilities(intel_sdvo, &intel_sdvo->caps))
 		goto err;
 
+	/* Set up hotplug command - note paranoia about contents of reply.
+	 * We assume that the hardware is in a sane state, and only touch
+	 * the bits we think we understand.
+	 */
+	intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_ACTIVE_HOT_PLUG,
+			     &intel_sdvo->hotplug_active, 2);
+	intel_sdvo->hotplug_active[0] &= ~0x3;
+
 	if (intel_sdvo_output_setup(intel_sdvo,
 				    intel_sdvo->caps.output_flags) != true) {
 		DRM_DEBUG_KMS("SDVO output failed to setup on SDVO%c\n",