disp: msm: dp: move fsa init from dp probe to dp hotplug

DP driver, at probe time, checks for fsa probe completion by
registering a notifier callback. The fsa driver performs some
I2C operations at this time. But occasionally, it takes multiple
attempts to complete these I2C transactions,adding huge delays
to display driver probing.If this delay is long enough, then
display usermode services start before display driver probe completes
and as a result, it fails to enumerate any displays.

Since the fsa switch is needed only after an external display is hot
plugged,this change moves the fsa probe check to dp hotplug handler.

Change-Id: I1b592ec3921a0b406ca23142d07e1a7e8b72090e
Signed-off-by: Vara Reddy <[email protected]>

msm/dp/dp_display.c

@@ -163,6 +163,7 @@ struct dp_display_private {
 
 	struct platform_device *pdev;
 	struct device_node *aux_switch_node;
+	bool aux_switch_ready;
 	struct dp_aux_bridge *aux_bridge;
 	struct dentry *root;
 	struct completion notification_comp;
@@ -1324,6 +1325,55 @@ static int dp_display_process_hpd_low(struct dp_display_private *dp)
 	return rc;
 }
 
+static int dp_display_fsa4480_callback(struct notifier_block *self,
+		unsigned long event, void *data)
+{
+	return 0;
+}
+
+static int dp_display_init_aux_switch(struct dp_display_private *dp)
+{
+	int rc = 0;
+	struct notifier_block nb;
+	const u32 max_retries = 50;
+	u32 retry;
+
+	if (dp->aux_switch_ready)
+	       return rc;
+
+	SDE_EVT32_EXTERNAL(SDE_EVTLOG_FUNC_ENTRY);
+
+	nb.notifier_call = dp_display_fsa4480_callback;
+	nb.priority = 0;
+
+	/*
+	 * Iteratively wait for reg notifier which confirms that fsa driver is probed.
+	 * Bootup DP with cable connected usecase can hit this scenario.
+	 */
+	for (retry = 0; retry < max_retries; retry++) {
+		rc = fsa4480_reg_notifier(&nb, dp->aux_switch_node);
+		if (rc == 0) {
+			DP_DEBUG("registered notifier successfully\n");
+			dp->aux_switch_ready = true;
+			break;
+		} else {
+			DP_DEBUG("failed to register notifier retry=%d rc=%d\n", retry, rc);
+			msleep(100);
+		}
+	}
+
+	if (retry == max_retries) {
+		DP_WARN("Failed to register fsa notifier\n");
+		dp->aux_switch_ready = false;
+		return rc;
+	}
+
+	fsa4480_unreg_notifier(&nb, dp->aux_switch_node);
+
+	SDE_EVT32_EXTERNAL(SDE_EVTLOG_FUNC_EXIT, rc);
+	return rc;
+}
+
 static int dp_display_usbpd_configure_cb(struct device *dev)
 {
 	int rc = 0;
@@ -1341,7 +1391,11 @@ static int dp_display_usbpd_configure_cb(struct device *dev)
 	}
 
 	if (!dp->debug->sim_mode && !dp->parser->no_aux_switch
-	    && !dp->parser->gpio_aux_switch) {
+	    && !dp->parser->gpio_aux_switch && dp->aux_switch_node) {
+		rc = dp_display_init_aux_switch(dp);
+		if (rc)
+			return rc;
+
 		rc = dp->aux->aux_switch(dp->aux, true, dp->hpd->orientation);
 		if (rc)
 			return rc;
@@ -1896,6 +1950,7 @@ static int dp_init_sub_modules(struct dp_display_private *dp)
 	int rc = 0;
 	u32 dp_core_revision = 0;
 	bool hdcp_disabled;
+	const char *phandle = "qcom,dp-aux-switch";
 	struct device *dev = &dp->pdev->dev;
 	struct dp_hpd_cb *cb = &dp->hpd_cb;
 	struct dp_ctrl_in ctrl_in = {
@@ -1940,6 +1995,10 @@ static int dp_init_sub_modules(struct dp_display_private *dp)
 
 	dp_core_revision = dp_catalog_get_dp_core_version(dp->catalog);
 
+	dp->aux_switch_node = of_parse_phandle(dp->pdev->dev.of_node, phandle, 0);
+	if (!dp->aux_switch_node)
+		DP_DEBUG("cannot parse %s handle\n", phandle);
+
 	dp->aux = dp_aux_get(dev, &dp->catalog->aux, dp->parser,
 			dp->aux_switch_node, dp->aux_bridge);
 	if (IS_ERR(dp->aux)) {
@@ -3047,48 +3106,6 @@ static int dp_display_create_workqueue(struct dp_display_private *dp)
 	return 0;
 }
 
-static int dp_display_fsa4480_callback(struct notifier_block *self,
-		unsigned long event, void *data)
-{
-	return 0;
-}
-
-static int dp_display_init_aux_switch(struct dp_display_private *dp)
-{
-	int rc = 0;
-	const char *phandle = "qcom,dp-aux-switch";
-	struct notifier_block nb;
-
-	if (!dp->pdev->dev.of_node) {
-		DP_ERR("cannot find dev.of_node\n");
-		rc = -ENODEV;
-		goto end;
-	}
-
-	SDE_EVT32_EXTERNAL(SDE_EVTLOG_FUNC_ENTRY);
-	dp->aux_switch_node = of_parse_phandle(dp->pdev->dev.of_node,
-			phandle, 0);
-	if (!dp->aux_switch_node) {
-		DP_WARN("cannot parse %s handle\n", phandle);
-		rc = -ENODEV;
-		goto end;
-	}
-
-	nb.notifier_call = dp_display_fsa4480_callback;
-	nb.priority = 0;
-
-	rc = fsa4480_reg_notifier(&nb, dp->aux_switch_node);
-	if (rc) {
-		DP_ERR("failed to register notifier (%d)\n", rc);
-		goto end;
-	}
-
-	fsa4480_unreg_notifier(&nb, dp->aux_switch_node);
-end:
-	SDE_EVT32_EXTERNAL(SDE_EVTLOG_FUNC_EXIT, rc);
-	return rc;
-}
-
 static int dp_display_bridge_internal_hpd(void *dev, bool hpd, bool hpd_irq)
 {
 	struct dp_display_private *dp = dev;
@@ -3502,12 +3519,6 @@ static int dp_display_probe(struct platform_device *pdev)
 
 	memset(&dp->mst, 0, sizeof(dp->mst));
 
-	rc = dp_display_init_aux_switch(dp);
-	if (rc) {
-		rc = -EPROBE_DEFER;
-		goto error;
-	}
-
 	rc = dp_display_init_aux_bridge(dp);
 	if (rc)
 		goto error;