[PATCH 1/2] drm: Add a new connector property for link status

[Manasi Navare]

A new optional connector property is added for keeping
track of whether the link is good (link training passed) or
link is bad (link training  failed). If the link status property
is Bad, then userspace should fire off a new modeset at the current
mode even if there have not been any changes in the mode list
or connector status.

Cc: dri-devel at lists.freedesktop.org
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at intel.com>
Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/drm_connector.c | 32 ++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h     |  1 +
 include/drm/drm_crtc.h          |  6 ++++++
 include/uapi/drm/drm_mode.h     |  4 ++++
 4 files changed, 43 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 2db7fb5..b4ce19f 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -588,6 +588,11 @@ int drm_display_info_set_bus_formats(struct drm_display_info *info,
 DRM_ENUM_NAME_FN(drm_get_tv_subconnector_name,
 		 drm_tv_subconnector_enum_list)
 
+static const struct drm_prop_enum_list drm_link_status_enum_list[] = {
+	{ DRM_MODE_LINK_STATUS_GOOD, "Good" },
+	{ DRM_MODE_LINK_STATUS_BAD, "Bad" },
+};
+
 int drm_connector_create_standard_properties(struct drm_device *dev)
 {
 	struct drm_property *prop;
@@ -845,6 +850,33 @@ int drm_mode_create_suggested_offset_properties(struct drm_device *dev)
 EXPORT_SYMBOL(drm_mode_create_suggested_offset_properties);
 
 /**
+ * drm_mode_create_link_status_property - Create link status property
+ * @dev: DRM device
+ *
+ * Called by a driver the first time it's needed, must be attached to desired
+ * connectors.
+ * This property is used to indicate whether link sttaus is Good or Bad as
+ * a result fo link training
+ */
+int drm_mode_create_link_status_property(struct drm_device *dev)
+{
+	struct drm_property *link_status;
+
+	if (dev->mode_config.link_status_property)
+		return 0;
+
+	link_status =
+		drm_property_create_enum(dev, 0, "link-status",
+					 drm_link_status_enum_list,
+					 ARRAY_SIZE(drm_link_status_enum_list));
+
+	dev->mode_config.scaling_mode_property = link_status;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_mode_create_link_status_property);
+
+/**
  * drm_mode_connector_set_path_property - set tile property on connector
  * @connector: connector to set property on.
  * @path: path to use for property; must not be NULL.
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index fc9d475..7234c0c 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -759,6 +759,7 @@ int drm_mode_create_tv_properties(struct drm_device *dev,
 int drm_mode_create_scaling_mode_property(struct drm_device *dev);
 int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
 int drm_mode_create_suggested_offset_properties(struct drm_device *dev);
+int drm_mode_create_link_status_property(struct drm_device *dev);
 
 int drm_mode_connector_set_path_property(struct drm_connector *connector,
 					 const char *path);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index fa1aa21..3e9c833 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1343,6 +1343,12 @@ struct drm_mode_config {
 	 */
 	struct drm_property *suggested_y_property;
 
+	/**
+	 * @link_status_property: Optional connector property for link status
+	 * of the connector as a result of link training.
+	 */
+	 struct drm_property *link_status_property;
+
 	/* dumb ioctl parameters */
 	uint32_t preferred_depth, prefer_shadow;
 
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 084b50a..f1b0afd 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -121,6 +121,10 @@
 #define DRM_MODE_DIRTY_ON       1
 #define DRM_MODE_DIRTY_ANNOTATE 2
 
+/* Link Status options */
+#define DRM_MODE_LINK_STATUS_GOOD	0
+#define DRM_MODE_LINK_STATUS_BAD	1
+
 struct drm_mode_modeinfo {
 	__u32 clock;
 	__u16 hdisplay;
-- 
1.9.1