From 3c5968002bb47556aff9c15939e8e15fb7f53756 Mon Sep 17 00:00:00 2001
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Date: Fri, 2 Jun 2017 15:26:35 +0300
Subject: [PATCH] drm/omap: Support for HDMI hot plug detection

The HPD signal can be used for detecting HDMI cable plug and unplug event
without the need for polling the status of the line.
This will speed up detecting such event because we do not need to wait for
the next poll event to notice the state change.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
---
 drivers/gpu/drm/omapdrm/dss/omapdss.h    | 17 +++++++++++
 drivers/gpu/drm/omapdrm/omap_connector.c | 37 +++++++++++++++++++++++-
 drivers/gpu/drm/omapdrm/omap_drv.c       | 29 +++++++++++++++++++
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/omapdss.h b/drivers/gpu/drm/omapdrm/dss/omapdss.h
index 85953a0bc7c2..b9b0bb27069a 100644
--- a/drivers/gpu/drm/omapdrm/dss/omapdss.h
+++ b/drivers/gpu/drm/omapdrm/dss/omapdss.h
@@ -25,6 +25,7 @@
 #include <video/videomode.h>
 #include <linux/platform_data/omapdss.h>
 #include <uapi/drm/drm_mode.h>
+#include <drm/drm_crtc.h>
 
 #define DISPC_IRQ_FRAMEDONE		(1 << 0)
 #define DISPC_IRQ_VSYNC			(1 << 1)
@@ -403,6 +404,14 @@ struct omapdss_hdmi_ops {
 	int (*read_edid)(struct omap_dss_device *dssdev, u8 *buf, int len);
 	bool (*detect)(struct omap_dss_device *dssdev);
 
+	int (*register_hpd_cb)(struct omap_dss_device *dssdev,
+			       void (*cb)(void *cb_data,
+					  enum drm_connector_status status),
+			       void *cb_data);
+	void (*unregister_hpd_cb)(struct omap_dss_device *dssdev);
+	void (*enable_hpd)(struct omap_dss_device *dssdev);
+	void (*disable_hpd)(struct omap_dss_device *dssdev);
+
 	int (*set_hdmi_mode)(struct omap_dss_device *dssdev, bool hdmi_mode);
 	int (*set_infoframe)(struct omap_dss_device *dssdev,
 		const struct hdmi_avi_infoframe *avi);
@@ -567,6 +576,14 @@ struct omap_dss_driver {
 	int (*read_edid)(struct omap_dss_device *dssdev, u8 *buf, int len);
 	bool (*detect)(struct omap_dss_device *dssdev);
 
+	int (*register_hpd_cb)(struct omap_dss_device *dssdev,
+			       void (*cb)(void *cb_data,
+					  enum drm_connector_status status),
+			       void *cb_data);
+	void (*unregister_hpd_cb)(struct omap_dss_device *dssdev);
+	void (*enable_hpd)(struct omap_dss_device *dssdev);
+	void (*disable_hpd)(struct omap_dss_device *dssdev);
+
 	int (*set_hdmi_mode)(struct omap_dss_device *dssdev, bool hdmi_mode);
 	int (*set_hdmi_infoframe)(struct omap_dss_device *dssdev,
 		const struct hdmi_avi_infoframe *avi);
diff --git a/drivers/gpu/drm/omapdrm/omap_connector.c b/drivers/gpu/drm/omapdrm/omap_connector.c
index d1ec76ef5cc6..aa5ba9ae2191 100644
--- a/drivers/gpu/drm/omapdrm/omap_connector.c
+++ b/drivers/gpu/drm/omapdrm/omap_connector.c
@@ -35,6 +35,23 @@ struct omap_connector {
 	bool hdmi_mode;
 };
 
+static void omap_connector_hpd_cb(void *cb_data,
+				  enum drm_connector_status status)
+{
+	struct omap_connector *omap_connector = cb_data;
+	struct drm_connector *connector = &omap_connector->base;
+	struct drm_device *dev = connector->dev;
+	enum drm_connector_status old_status;
+
+	mutex_lock(&dev->mode_config.mutex);
+	old_status = connector->status;
+	connector->status = status;
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (old_status != status)
+		drm_kms_helper_hotplug_event(dev);
+}
+
 bool omap_connector_get_hdmi_mode(struct drm_connector *connector)
 {
 	struct omap_connector *omap_connector = to_omap_connector(connector);
@@ -75,6 +92,10 @@ static void omap_connector_destroy(struct drm_connector *connector)
 	struct omap_dss_device *dssdev = omap_connector->dssdev;
 
 	DBG("%s", omap_connector->dssdev->name);
+	if (connector->polled == DRM_CONNECTOR_POLL_HPD &&
+	    dssdev->driver->unregister_hpd_cb) {
+		dssdev->driver->unregister_hpd_cb(dssdev);
+	}
 	drm_connector_unregister(connector);
 	drm_connector_cleanup(connector);
 	kfree(omap_connector);
@@ -215,6 +236,7 @@ struct drm_connector *omap_connector_init(struct drm_device *dev,
 {
 	struct drm_connector *connector = NULL;
 	struct omap_connector *omap_connector;
+	bool hpd_supported = false;
 
 	DBG("%s", dssdev->name);
 
@@ -232,7 +254,20 @@ struct drm_connector *omap_connector_init(struct drm_device *dev,
 				connector_type);
 	drm_connector_helper_add(connector, &omap_connector_helper_funcs);
 
-	if (dssdev->driver->detect)
+	if (dssdev->driver->register_hpd_cb) {
+		int ret = dssdev->driver->register_hpd_cb(dssdev,
+							  omap_connector_hpd_cb,
+							  omap_connector);
+		if (!ret)
+			hpd_supported = true;
+		else if (ret != -ENOTSUPP)
+			DBG("%s: Failed to register HPD callback (%d).",
+			    dssdev->name, ret);
+	}
+
+	if (hpd_supported)
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	else if (dssdev->driver->detect)
 		connector->polled = DRM_CONNECTOR_POLL_CONNECT |
 				    DRM_CONNECTOR_POLL_DISCONNECT;
 	else
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index 721a358531b0..10e24ca928f2 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -323,6 +323,32 @@ static int omap_modeset_init(struct drm_device *dev)
 	return 0;
 }
 
+/*
+ * Enable the HPD in external components if supported
+ */
+static void omap_modeset_enable_external_hpd(void)
+{
+	struct omap_dss_device *dssdev = NULL;
+
+	for_each_dss_dev(dssdev) {
+		if (dssdev->driver->enable_hpd)
+			dssdev->driver->enable_hpd(dssdev);
+	}
+}
+
+/*
+ * Disable the HPD in external components if supported
+ */
+static void omap_modeset_disable_external_hpd(void)
+{
+	struct omap_dss_device *dssdev = NULL;
+
+	for_each_dss_dev(dssdev) {
+		if (dssdev->driver->disable_hpd)
+			dssdev->driver->disable_hpd(dssdev);
+	}
+}
+
 /*
  * drm ioctl funcs
  */
@@ -602,6 +628,7 @@ static int pdev_probe(struct platform_device *pdev)
 	priv->fbdev = omap_fbdev_init(ddev);
 
 	drm_kms_helper_poll_init(ddev);
+	omap_modeset_enable_external_hpd();
 
 	/*
 	 * Register the DRM device with the core and the connectors with
@@ -614,6 +641,7 @@ static int pdev_probe(struct platform_device *pdev)
 	return 0;
 
 err_cleanup_helpers:
+	omap_modeset_disable_external_hpd();
 	drm_kms_helper_poll_fini(ddev);
 	if (priv->fbdev)
 		omap_fbdev_free(ddev);
@@ -642,6 +670,7 @@ static int pdev_remove(struct platform_device *pdev)
 
 	drm_dev_unregister(ddev);
 
+	omap_modeset_disable_external_hpd();
 	drm_kms_helper_poll_fini(ddev);
 
 	if (priv->fbdev)
-- 
2.45.2