drm: Store the plane's index

Currently the plane's index is determined by walking the list of all
planes in the mode and finding the position of that plane in the list. A
linear walk, especially a linear walk within a linear walk as frequently
conceived by i915.ko [O(N^2)] quickly comes to dominate profiles.

The plane's index is constant for as long as no earlier planes are
removed from the list. For all drivers, planes are static, determined
at boot and then untouched until shutdown. In fact, there is no locking
provided to allow for dynamic removal of planes/encoders/crtcs.

v2: Convert drm_crtc_index() and drm_encoder_index() as well.
v3: Stop adjusting the indices upon removal; consider the list
construct-only.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
[danvet: Fixup typo in kerneldoc that Matt spotted.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464375900-2542-1-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/drm_crtc.c

@@ -692,7 +692,7 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
 	crtc->base.properties = &crtc->properties;
 
 	list_add_tail(&crtc->head, &config->crtc_list);
-	config->num_crtc++;
+	crtc->index = config->num_crtc++;
 
 	crtc->primary = primary;
 	crtc->cursor = cursor;
@@ -722,6 +722,11 @@ void drm_crtc_cleanup(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 
+	/* Note that the crtc_list is considered to be static; should we
+	 * remove the drm_crtc at runtime we would have to decrement all
+	 * the indices on the drm_crtc after us in the crtc_list.
+	 */
+
 	kfree(crtc->gamma_store);
 	crtc->gamma_store = NULL;
 
@@ -741,29 +746,6 @@ void drm_crtc_cleanup(struct drm_crtc *crtc)
 }
 EXPORT_SYMBOL(drm_crtc_cleanup);
 
-/**
- * drm_crtc_index - find the index of a registered CRTC
- * @crtc: CRTC to find index for
- *
- * Given a registered CRTC, return the index of that CRTC within a DRM
- * device's list of CRTCs.
- */
-unsigned int drm_crtc_index(struct drm_crtc *crtc)
-{
-	unsigned int index = 0;
-	struct drm_crtc *tmp;
-
-	drm_for_each_crtc(tmp, crtc->dev) {
-		if (tmp == crtc)
-			return index;
-
-		index++;
-	}
-
-	BUG();
-}
-EXPORT_SYMBOL(drm_crtc_index);
-
 /*
  * drm_mode_remove - remove and free a mode
  * @connector: connector list to modify
@@ -1166,7 +1148,7 @@ int drm_encoder_init(struct drm_device *dev,
 	}
 
 	list_add_tail(&encoder->head, &dev->mode_config.encoder_list);
-	dev->mode_config.num_encoder++;
+	encoder->index = dev->mode_config.num_encoder++;
 
 out_put:
 	if (ret)
@@ -1179,29 +1161,6 @@ out_unlock:
 }
 EXPORT_SYMBOL(drm_encoder_init);
 
-/**
- * drm_encoder_index - find the index of a registered encoder
- * @encoder: encoder to find index for
- *
- * Given a registered encoder, return the index of that encoder within a DRM
- * device's list of encoders.
- */
-unsigned int drm_encoder_index(struct drm_encoder *encoder)
-{
-	unsigned int index = 0;
-	struct drm_encoder *tmp;
-
-	drm_for_each_encoder(tmp, encoder->dev) {
-		if (tmp == encoder)
-			return index;
-
-		index++;
-	}
-
-	BUG();
-}
-EXPORT_SYMBOL(drm_encoder_index);
-
 /**
  * drm_encoder_cleanup - cleans up an initialised encoder
  * @encoder: encoder to cleanup
@@ -1212,6 +1171,11 @@ void drm_encoder_cleanup(struct drm_encoder *encoder)
 {
 	struct drm_device *dev = encoder->dev;
 
+	/* Note that the encoder_list is considered to be static; should we
+	 * remove the drm_encoder at runtime we would have to decrement all
+	 * the indices on the drm_encoder after us in the encoder_list.
+	 */
+
 	drm_modeset_lock_all(dev);
 	drm_mode_object_unregister(dev, &encoder->base);
 	kfree(encoder->name);
@@ -1300,7 +1264,7 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
 	plane->type = type;
 
 	list_add_tail(&plane->head, &config->plane_list);
-	config->num_total_plane++;
+	plane->index = config->num_total_plane++;
 	if (plane->type == DRM_PLANE_TYPE_OVERLAY)
 		config->num_overlay_plane++;
 
@@ -1374,6 +1338,11 @@ void drm_plane_cleanup(struct drm_plane *plane)
 
 	BUG_ON(list_empty(&plane->head));
 
+	/* Note that the plane_list is considered to be static; should we
+	 * remove the drm_plane at runtime we would have to decrement all
+	 * the indices on the drm_plane after us in the plane_list.
+	 */
+
 	list_del(&plane->head);
 	dev->mode_config.num_total_plane--;
 	if (plane->type == DRM_PLANE_TYPE_OVERLAY)
@@ -1390,29 +1359,6 @@ void drm_plane_cleanup(struct drm_plane *plane)
 }
 EXPORT_SYMBOL(drm_plane_cleanup);
 
-/**
- * drm_plane_index - find the index of a registered plane
- * @plane: plane to find index for
- *
- * Given a registered plane, return the index of that CRTC within a DRM
- * device's list of planes.
- */
-unsigned int drm_plane_index(struct drm_plane *plane)
-{
-	unsigned int index = 0;
-	struct drm_plane *tmp;
-
-	drm_for_each_plane(tmp, plane->dev) {
-		if (tmp == plane)
-			return index;
-
-		index++;
-	}
-
-	BUG();
-}
-EXPORT_SYMBOL(drm_plane_index);
-
 /**
  * drm_plane_from_index - find the registered plane at an index
  * @dev: DRM device
@@ -1425,13 +1371,11 @@ struct drm_plane *
 drm_plane_from_index(struct drm_device *dev, int idx)
 {
 	struct drm_plane *plane;
-	unsigned int i = 0;
 
-	drm_for_each_plane(plane, dev) {
-		if (i == idx)
+	drm_for_each_plane(plane, dev)
+		if (idx == plane->index)
 			return plane;
-		i++;
-	}
+
 	return NULL;
 }
 EXPORT_SYMBOL(drm_plane_from_index);

include/drm/drm_crtc.h

@@ -753,6 +753,9 @@ struct drm_crtc {
 	struct drm_plane *primary;
 	struct drm_plane *cursor;
 
+	/* position inside the mode_config.list, can be used as a [] idx */
+	unsigned index;
+
 	/* position of cursor plane on crtc */
 	int cursor_x;
 	int cursor_y;
@@ -1097,6 +1100,10 @@ struct drm_encoder {
 	struct drm_mode_object base;
 	char *name;
 	int encoder_type;
+
+	/* position inside the mode_config.list, can be used as a [] idx */
+	unsigned index;
+
 	uint32_t possible_crtcs;
 	uint32_t possible_clones;
 
@@ -1543,6 +1550,9 @@ struct drm_plane {
 
 	enum drm_plane_type type;
 
+	/* position inside the mode_config.list, can be used as a [] idx */
+	unsigned index;
+
 	const struct drm_plane_helper_funcs *helper_private;
 
 	struct drm_plane_state *state;
@@ -2240,7 +2250,18 @@ int drm_crtc_init_with_planes(struct drm_device *dev,
 			      const struct drm_crtc_funcs *funcs,
 			      const char *name, ...);
 extern void drm_crtc_cleanup(struct drm_crtc *crtc);
-extern unsigned int drm_crtc_index(struct drm_crtc *crtc);
+
+/**
+ * drm_crtc_index - find the index of a registered CRTC
+ * @crtc: CRTC to find index for
+ *
+ * Given a registered CRTC, return the index of that CRTC within a DRM
+ * device's list of CRTCs.
+ */
+static inline unsigned int drm_crtc_index(struct drm_crtc *crtc)
+{
+	return crtc->index;
+}
 
 /**
  * drm_crtc_mask - find the mask of a registered CRTC
@@ -2294,7 +2315,18 @@ int drm_encoder_init(struct drm_device *dev,
 		     struct drm_encoder *encoder,
 		     const struct drm_encoder_funcs *funcs,
 		     int encoder_type, const char *name, ...);
-extern unsigned int drm_encoder_index(struct drm_encoder *encoder);
+
+/**
+ * drm_encoder_index - find the index of a registered encoder
+ * @encoder: encoder to find index for
+ *
+ * Given a registered encoder, return the index of that encoder within a DRM
+ * device's list of encoders.
+ */
+static inline unsigned int drm_encoder_index(struct drm_encoder *encoder)
+{
+	return encoder->index;
+}
 
 /**
  * drm_encoder_crtc_ok - can a given crtc drive a given encoder?
@@ -2325,7 +2357,18 @@ extern int drm_plane_init(struct drm_device *dev,
 			  const uint32_t *formats, unsigned int format_count,
 			  bool is_primary);
 extern void drm_plane_cleanup(struct drm_plane *plane);
-extern unsigned int drm_plane_index(struct drm_plane *plane);
+
+/**
+ * drm_plane_index - find the index of a registered plane
+ * @plane: plane to find index for
+ *
+ * Given a registered plane, return the index of that plane within a DRM
+ * device's list of planes.
+ */
+static inline unsigned int drm_plane_index(struct drm_plane *plane)
+{
+	return plane->index;
+}
 extern struct drm_plane * drm_plane_from_index(struct drm_device *dev, int idx);
 extern void drm_plane_force_disable(struct drm_plane *plane);
 extern int drm_plane_check_pixel_format(const struct drm_plane *plane,