libweston: Compute current protection for weston_output and weston_head

The actual protection status for a given weston_head depends upon the
corresponding drm_head's connector HDCP properties. On the other hand,
the actual protection for a weston_output is the minimum of the
protection status of its attached heads.
As a head's protection changes, the current protection of the output
to which the head is attached is recomputed.

This patch adds the support to keep track of the current
content-protection for heads and the outputs.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>

include/libweston/libweston.h

@@ -215,6 +215,9 @@ struct weston_head {
 	char *name;			/**< head name, e.g. connector name */
 	bool connected;			/**< is physically connected */
 	bool non_desktop;		/**< non-desktop display, e.g. HMD */
+
+	/** Current content protection status */
+	enum weston_hdcp_protection current_protection;
 };
 
 /** Represents an output
@@ -292,6 +295,7 @@ struct weston_output {
 	struct wl_list head_list; /**< List of driven weston_heads */
 
 	enum weston_hdcp_protection desired_protection;
+	enum weston_hdcp_protection current_protection;
 
 	void (*start_repaint_loop)(struct weston_output *output);
 	int (*repaint)(struct weston_output *output,
@@ -2355,6 +2359,10 @@ struct wl_listener *
 weston_head_get_destroy_listener(struct weston_head *head,
 				 wl_notify_func_t notify);
 
+void
+weston_head_set_content_protection_status(struct weston_head *head,
+					  enum weston_hdcp_protection status);
+
 struct weston_head *
 weston_compositor_iterate_heads(struct weston_compositor *compositor,
 				struct weston_head *iter);

libweston/compositor.c

@@ -4769,6 +4769,7 @@ weston_head_init(struct weston_head *head, const char *name)
 	wl_list_init(&head->resource_list);
 	wl_list_init(&head->xdg_output_resource_list);
 	head->name = strdup(name);
+	head->current_protection = WESTON_HDCP_DISABLE;
 }
 
 /** Send output heads changed signal
@@ -5271,6 +5272,38 @@ weston_head_set_connection_status(struct weston_head *head, bool connected)
 	weston_head_set_device_changed(head);
 }
 
+static void
+weston_output_compute_protection(struct weston_output *output)
+{
+	struct weston_head *head;
+	enum weston_hdcp_protection op_protection;
+	bool op_protection_valid = false;
+
+	wl_list_for_each(head, &output->head_list, output_link) {
+		if (!op_protection_valid) {
+			op_protection = head->current_protection;
+			op_protection_valid = true;
+		}
+		if (head->current_protection < op_protection)
+			op_protection = head->current_protection;
+	}
+
+	if (!op_protection_valid)
+		op_protection = WESTON_HDCP_DISABLE;
+
+	if (output->current_protection != op_protection)
+		output->current_protection = op_protection;
+}
+
+WL_EXPORT void
+weston_head_set_content_protection_status(struct weston_head *head,
+					  enum weston_hdcp_protection status)
+{
+	head->current_protection = status;
+	if (head->output)
+		weston_output_compute_protection(head->output);
+}
+
 /** Is the head currently connected?
  *
  * \param head The head to query.