drm/exynos: add pm_runtime to DP

Let pm_runtime handle the enabling/disabling of the device with
proper refcnt instead of rely on specific flags to track the enabled
state.

Chnagelog v3:
- revive dpms_mode to keep current dpms mode.

Changelog v2:
- no change
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_dp_core.c

@@ -1061,6 +1061,8 @@ static void exynos_dp_bridge_enable(struct drm_bridge *bridge)
 	if (dp->dpms_mode == DRM_MODE_DPMS_ON)
 		return;
 
+	pm_runtime_get_sync(dp->dev);
+
 	if (dp->panel) {
 		if (drm_panel_prepare(dp->panel)) {
 			DRM_ERROR("failed to setup the panel\n");
@@ -1071,7 +1073,6 @@ static void exynos_dp_bridge_enable(struct drm_bridge *bridge)
 	if (crtc->ops->clock_enable)
 		crtc->ops->clock_enable(dp_to_crtc(dp), true);
 
-	clk_prepare_enable(dp->clock);
 	phy_power_on(dp->phy);
 	exynos_dp_init_dp(dp);
 	enable_irq(dp->irq);
@@ -1098,7 +1099,6 @@ static void exynos_dp_bridge_disable(struct drm_bridge *bridge)
 	disable_irq(dp->irq);
 	flush_work(&dp->hotplug_work);
 	phy_power_off(dp->phy);
-	clk_disable_unprepare(dp->clock);
 
 	if (crtc->ops->clock_enable)
 		crtc->ops->clock_enable(dp_to_crtc(dp), false);
@@ -1108,6 +1108,8 @@ static void exynos_dp_bridge_disable(struct drm_bridge *bridge)
 			DRM_ERROR("failed to turnoff the panel\n");
 	}
 
+	pm_runtime_put_sync(dp->dev);
+
 	dp->dpms_mode = DRM_MODE_DPMS_OFF;
 }
 
@@ -1392,6 +1394,7 @@ static int exynos_dp_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct device_node *panel_node, *bridge_node, *endpoint;
 	struct exynos_dp_device *dp;
+	int ret;
 
 	dp = devm_kzalloc(&pdev->dev, sizeof(struct exynos_dp_device),
 				GFP_KERNEL);
@@ -1420,16 +1423,57 @@ static int exynos_dp_probe(struct platform_device *pdev)
 			return -EPROBE_DEFER;
 	}
 
-	return component_add(&pdev->dev, &exynos_dp_ops);
+	pm_runtime_enable(dev);
+
+	ret = component_add(&pdev->dev, &exynos_dp_ops);
+	if (ret)
+		goto err_disable_pm_runtime;
+
+	return ret;
+
+err_disable_pm_runtime:
+	pm_runtime_disable(dev);
+
+	return ret;
 }
 
 static int exynos_dp_remove(struct platform_device *pdev)
 {
+	pm_runtime_disable(&pdev->dev);
 	component_del(&pdev->dev, &exynos_dp_ops);
 
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int exynos_dp_suspend(struct device *dev)
+{
+	struct exynos_dp_device *dp = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(dp->clock);
+
+	return 0;
+}
+
+static int exynos_dp_resume(struct device *dev)
+{
+	struct exynos_dp_device *dp = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(dp->clock);
+	if (ret < 0) {
+		DRM_ERROR("Failed to prepare_enable the clock clk [%d]\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops exynos_dp_pm_ops = {
+	SET_RUNTIME_PM_OPS(exynos_dp_suspend, exynos_dp_resume, NULL)
+};
+
 static const struct of_device_id exynos_dp_match[] = {
 	{ .compatible = "samsung,exynos5-dp" },
 	{},
@@ -1442,6 +1486,7 @@ struct platform_driver dp_driver = {
 	.driver		= {
 		.name	= "exynos-dp",
 		.owner	= THIS_MODULE,
+		.pm	= &exynos_dp_pm_ops,
 		.of_match_table = exynos_dp_match,
 	},
 };