drm: introduce generation counter to interface.

Idea being if you want to add new crtc/output/encoder dynamically later,
you just increase the generation counter and userspace should re-read
all the resources

4 files changed, 25 insertions, 2 deletions

diff --git a/libdrm/xf86drmMode.h b/libdrm/xf86drmMode.h
index 56908d8f..3bd30a92 100644
--- a/libdrm/xf86drmMode.h
+++ b/libdrm/xf86drmMode.h
@@ -51,9 +51,16 @@
  * buffer object interface. This object needs to be pinned.
  */
 
+/*
+ * generation - these are to be read by userspace, and if it notices
+ * while calling a get output or get crtc that the generation has changed
+ * it should re-call the mode resource functions resync its view of the
+ * outputs with current view.
+ */
 
 typedef struct _drmModeRes {
 
+	uint32_t generation;
 	int count_fbs;
 	uint32_t *fbs;
 
@@ -93,6 +100,7 @@ typedef struct _drmModeProperty {
 typedef struct _drmModeCrtc {
 	unsigned int crtc_id;
 	unsigned int buffer_id; /**< FB id to connect to 0 = disconnect*/
+	uint32_t generation;
 
 	uint32_t x, y; /**< Position on the frameuffer */
 	uint32_t width, height;
@@ -110,6 +118,7 @@ typedef struct _drmModeCrtc {
 } drmModeCrtc, *drmModeCrtcPtr;
 
 typedef struct _drmModeEncoder {
+	uint32_t generation;
 	unsigned int encoder_id;
 	unsigned int encoder_type;
 	uint32_t crtc;
@@ -133,8 +142,8 @@ typedef enum {
 } drmModeSubPixel;
 
 typedef struct _drmModeConnector {
+	uint32_t generation;
 	unsigned int connector_id;
-
 	unsigned int encoder; /**< Crtc currently connected to */
 	unsigned int connector_type;
 	unsigned int connector_type_id;
diff --git a/linux-core/drm_crtc.c b/linux-core/drm_crtc.c
index d2060fd1..4c6afd16 100644
--- a/linux-core/drm_crtc.c
+++ b/linux-core/drm_crtc.c
@@ -571,6 +571,7 @@ void drm_mode_config_init(struct drm_device *dev)
 	drm_mode_create_standard_connector_properties(dev);
 
 	/* Just to be sure */
+	dev->mode_config.current_generation = 0;
 	dev->mode_config.num_fb = 0;
 	dev->mode_config.num_connector = 0;
 	dev->mode_config.num_crtc = 0;
@@ -801,6 +802,7 @@ int drm_mode_getresources(struct drm_device *dev,
 	card_res->min_height = dev->mode_config.min_height;
 	card_res->max_width = dev->mode_config.max_width;
 	card_res->min_width = dev->mode_config.min_width;
+	card_res->generation = dev->mode_config.current_generation;
 
 	/* handle this in 4 parts */
 	/* FBs */
@@ -943,7 +945,7 @@ int drm_mode_getcrtc(struct drm_device *dev,
 	crtc_resp->x = crtc->x;
 	crtc_resp->y = crtc->y;
 	crtc_resp->gamma_size = crtc->gamma_size;
-
+	crtc_resp->generation = dev->mode_config.current_generation;
 	if (crtc->fb)
 		crtc_resp->fb_id = crtc->fb->base.id;
 	else
@@ -1032,6 +1034,7 @@ int drm_mode_getconnector(struct drm_device *dev,
 		connector->funcs->fill_modes(connector, dev->mode_config.max_width, dev->mode_config.max_height);
 	}
 
+	out_resp->generation = dev->mode_config.current_generation;
 	out_resp->connector_type = connector->connector_type;
 	out_resp->connector_type_id = connector->connector_type_id;
 	out_resp->mm_width = connector->display_info.width_mm;
@@ -1120,6 +1123,7 @@ int drm_mode_getencoder(struct drm_device *dev,
 		enc_resp->crtc = encoder->crtc->base.id;
 	else
 		enc_resp->crtc = 0;
+	enc_resp->generation = dev->mode_config.current_generation;
 	enc_resp->encoder_type = encoder->encoder_type;
 	enc_resp->encoder_id = encoder->base.id;
 	enc_resp->crtcs = encoder->possible_crtcs;
diff --git a/linux-core/drm_crtc.h b/linux-core/drm_crtc.h
index c92c59bf..f3953692 100644
--- a/linux-core/drm_crtc.h
+++ b/linux-core/drm_crtc.h
@@ -554,6 +554,9 @@ struct drm_mode_config {
 
 	struct list_head property_list;
 
+	/* currently in use generation id */
+	int current_generation;
+
 	int min_width, min_height;
 	int max_width, max_height;
 	struct drm_mode_config_funcs *funcs;
diff --git a/shared-core/drm.h b/shared-core/drm.h
index 132c7746..40653b4b 100644
--- a/shared-core/drm.h
+++ b/shared-core/drm.h
@@ -1033,6 +1033,7 @@ struct drm_mode_card_res {
 	int count_encoders;
 	int min_width, max_width;
 	int min_height, max_height;
+	uint32_t generation;
 };
 
 struct drm_mode_crtc {
@@ -1043,6 +1044,8 @@ struct drm_mode_crtc {
 
 	int x, y; /**< Position on the frameuffer */
 
+	uint32_t generation;
+
 	int count_connectors;
 	unsigned int connectors; /**< Connectors that are connected */
 
@@ -1055,6 +1058,8 @@ struct drm_mode_crtc {
 
 struct drm_mode_get_encoder {
 
+	uint32_t generation;
+
 	uint32_t encoder_type;
 	uint32_t encoder_id;
 
@@ -1085,6 +1090,8 @@ struct drm_mode_get_connector {
 	unsigned int connector_type;
 	unsigned int connector_type_id;
 
+	uint32_t generation;
+
 	unsigned int connection;
 	unsigned int mm_width, mm_height; /**< HxW in millimeters */
 	unsigned int subpixel;