drm: add generic zpos property

version 8:
- move drm_blend.o from drm-y to drm_kms_helper-y to avoid
  EXPORT_SYMBOL(drm_atomic_helper_normalize_zpos)
- remove dead function declarations in drm_crtc.h

version 7:
- remove useless EXPORT_SYMBOL()
- better z-order wording in Documentation

version 6:
- add zpos in gpu documentation file
- merge Ville patch about zpos initial value and API improvement.
  I have split Ville patch between zpos core and drivers

version 5:
- remove zpos range check and comeback to 0 to N-1
  normalization algorithm

version 4:
- make sure that normalized zpos value is stay
  in the defined property range and warn user if not

This patch adds support for generic plane's zpos property property with
well-defined semantics:
- added zpos properties to plane and plane state structures
- added helpers for normalizing zpos properties of given set of planes
- well defined semantics: planes are sorted by zpos values and then plane
  id value if zpos equals

Normalized zpos values are calculated automatically when generic
muttable zpos property has been initialized. Drivers can simply use
plane_state->normalized_zpos in their atomic_check and/or plane_update
callbacks without any additional calls to DRM core.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Compare to Marek's original patch zpos property is now specific to each
plane and no more to the core.
Normalize function take care of the range of per plane defined range
before set normalized_zpos.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Cc: Inki Dae <inki.dae@samsung.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: vincent.abriou@st.com
Cc: fabien.dessenne@st.com
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Documentation/gpu/kms-properties.csv

@@ -17,6 +17,7 @@ DRM,Generic,“rotation”,BITMASK,"{ 0, ""rotate-0"" }, { 1, ""rotate-90"" }, {
 ,,“CRTC_H”,RANGE,"Min=0, Max=UINT_MAX",Plane,Scanout CRTC (destination) height (atomic)
 ,,“FB_ID”,OBJECT,DRM_MODE_OBJECT_FB,Plane,Scanout framebuffer (atomic)
 ,,“CRTC_ID”,OBJECT,DRM_MODE_OBJECT_CRTC,Plane,CRTC that plane is attached to (atomic)
+,,“zpos”,RANGE,"Min=0, Max=UINT_MAX","Plane,Z-order of the plane.Planes with higher Z-order values are displayed on top, planes with identical Z-order values are display in an undefined order"
 ,DVI-I,“subconnector”,ENUM,"{ “Unknown”, “DVI-D”, “DVI-A” }",Connector,TBD
 ,,“select subconnector”,ENUM,"{ “Automatic”, “DVI-D”, “DVI-A” }",Connector,TBD
 ,TV,“subconnector”,ENUM,"{ ""Unknown"", ""Composite"", ""SVIDEO"", ""Component"", ""SCART"" }",Connector,TBD

drivers/gpu/drm/Makefile

@@ -24,7 +24,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
 drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
 		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
 		drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
-		drm_simple_kms_helper.o
+		drm_simple_kms_helper.o drm_blend.o
 
 drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o

drivers/gpu/drm/drm_atomic.c

@@ -711,6 +711,8 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
 		state->src_h = val;
 	} else if (property == config->rotation_property) {
 		state->rotation = val;
+	} else if (property == plane->zpos_property) {
+		state->zpos = val;
 	} else if (plane->funcs->atomic_set_property) {
 		return plane->funcs->atomic_set_property(plane, state,
 				property, val);
@@ -767,6 +769,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
 		*val = state->src_h;
 	} else if (property == config->rotation_property) {
 		*val = state->rotation;
+	} else if (property == plane->zpos_property) {
+		*val = state->zpos;
 	} else if (plane->funcs->atomic_get_property) {
 		return plane->funcs->atomic_get_property(plane, state, property, val);
 	} else {

drivers/gpu/drm/drm_atomic_helper.c

@@ -32,6 +32,8 @@
 #include <drm/drm_atomic_helper.h>
 #include <linux/fence.h>
 
+#include "drm_crtc_internal.h"
+
 /**
  * DOC: overview
  *
@@ -592,6 +594,10 @@ drm_atomic_helper_check_planes(struct drm_device *dev,
 	struct drm_plane_state *plane_state;
 	int i, ret = 0;
 
+	ret = drm_atomic_helper_normalize_zpos(dev, state);
+	if (ret)
+		return ret;
+
 	for_each_plane_in_state(state, plane, plane_state, i) {
 		const struct drm_plane_helper_funcs *funcs;
 
@@ -2955,6 +2961,7 @@ void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
 	state->planes_changed = false;
 	state->connectors_changed = false;
 	state->color_mgmt_changed = false;
+	state->zpos_changed = false;
 	state->event = NULL;
 }
 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);

drivers/gpu/drm/drm_blend.c

+/*
+ * Copyright (C) 2016 Samsung Electronics Co.Ltd
+ * Authors:
+ *	Marek Szyprowski <m.szyprowski@samsung.com>
+ *
+ * DRM core plane blending related functions
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+#include <drm/drmP.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_crtc.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+
+#include "drm_internal.h"
+
+/**
+ * drm_plane_create_zpos_property - create mutable zpos property
+ * @plane: drm plane
+ * @zpos: initial value of zpos property
+ * @min: minimal possible value of zpos property
+ * @max: maximal possible value of zpos property
+ *
+ * This function initializes generic mutable zpos property and enables support
+ * for it in drm core. Drivers can then attach this property to planes to enable
+ * support for configurable planes arrangement during blending operation.
+ * Once mutable zpos property has been enabled, the DRM core will automatically
+ * calculate drm_plane_state->normalized_zpos values. Usually min should be set
+ * to 0 and max to maximal number of planes for given crtc - 1.
+ *
+ * If zpos of some planes cannot be changed (like fixed background or
+ * cursor/topmost planes), driver should adjust min/max values and assign those
+ * planes immutable zpos property with lower or higher values (for more
+ * information, see drm_mode_create_zpos_immutable_property() function). In such
+ * case driver should also assign proper initial zpos values for all planes in
+ * its plane_reset() callback, so the planes will be always sorted properly.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_plane_create_zpos_property(struct drm_plane *plane,
+				   unsigned int zpos,
+				   unsigned int min, unsigned int max)
+{
+	struct drm_property *prop;
+
+	prop = drm_property_create_range(plane->dev, 0, "zpos", min, max);
+	if (!prop)
+		return -ENOMEM;
+
+	drm_object_attach_property(&plane->base, prop, zpos);
+
+	plane->zpos_property = prop;
+
+	if (plane->state) {
+		plane->state->zpos = zpos;
+		plane->state->normalized_zpos = zpos;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_plane_create_zpos_property);
+
+/**
+ * drm_plane_create_zpos_immutable_property - create immuttable zpos property
+ * @plane: drm plane
+ * @zpos: value of zpos property
+ *
+ * This function initializes generic immutable zpos property and enables
+ * support for it in drm core. Using this property driver lets userspace
+ * to get the arrangement of the planes for blending operation and notifies
+ * it that the hardware (or driver) doesn't support changing of the planes'
+ * order.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
+					     unsigned int zpos)
+{
+	struct drm_property *prop;
+
+	prop = drm_property_create_range(plane->dev, DRM_MODE_PROP_IMMUTABLE,
+					 "zpos", zpos, zpos);
+	if (!prop)
+		return -ENOMEM;
+
+	drm_object_attach_property(&plane->base, prop, zpos);
+
+	plane->zpos_property = prop;
+
+	if (plane->state) {
+		plane->state->zpos = zpos;
+		plane->state->normalized_zpos = zpos;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_plane_create_zpos_immutable_property);
+
+static int drm_atomic_state_zpos_cmp(const void *a, const void *b)
+{
+	const struct drm_plane_state *sa = *(struct drm_plane_state **)a;
+	const struct drm_plane_state *sb = *(struct drm_plane_state **)b;
+
+	if (sa->zpos != sb->zpos)
+		return sa->zpos - sb->zpos;
+	else
+		return sa->plane->base.id - sb->plane->base.id;
+}
+
+/**
+ * drm_atomic_helper_crtc_normalize_zpos - calculate normalized zpos values
+ * @crtc: crtc with planes, which have to be considered for normalization
+ * @crtc_state: new atomic state to apply
+ *
+ * This function checks new states of all planes assigned to given crtc and
+ * calculates normalized zpos value for them. Planes are compared first by their
+ * zpos values, then by plane id (if zpos equals). Plane with lowest zpos value
+ * is at the bottom. The plane_state->normalized_zpos is then filled with unique
+ * values from 0 to number of active planes in crtc minus one.
+ *
+ * RETURNS
+ * Zero for success or -errno
+ */
+static int drm_atomic_helper_crtc_normalize_zpos(struct drm_crtc *crtc,
+					  struct drm_crtc_state *crtc_state)
+{
+	struct drm_atomic_state *state = crtc_state->state;
+	struct drm_device *dev = crtc->dev;
+	int total_planes = dev->mode_config.num_total_plane;
+	struct drm_plane_state **states;
+	struct drm_plane *plane;
+	int i, n = 0;
+	int ret = 0;
+
+	DRM_DEBUG_ATOMIC("[CRTC:%d:%s] calculating normalized zpos values\n",
+			 crtc->base.id, crtc->name);
+
+	states = kmalloc_array(total_planes, sizeof(*states), GFP_TEMPORARY);
+	if (!states)
+		return -ENOMEM;
+
+	/*
+	 * Normalization process might create new states for planes which
+	 * normalized_zpos has to be recalculated.
+	 */
+	drm_for_each_plane_mask(plane, dev, crtc_state->plane_mask) {
+		struct drm_plane_state *plane_state =
+			drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state)) {
+			ret = PTR_ERR(plane_state);
+			goto done;
+		}
+		states[n++] = plane_state;
+		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] processing zpos value %d\n",
+				 plane->base.id, plane->name,
+				 plane_state->zpos);
+	}
+
+	sort(states, n, sizeof(*states), drm_atomic_state_zpos_cmp, NULL);
+
+	for (i = 0; i < n; i++) {
+		plane = states[i]->plane;
+
+		states[i]->normalized_zpos = i;
+		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] normalized zpos value %d\n",
+				 plane->base.id, plane->name, i);
+	}
+	crtc_state->zpos_changed = true;
+
+done:
+	kfree(states);
+	return ret;
+}
+
+/**
+ * drm_atomic_helper_normalize_zpos - calculate normalized zpos values for all
+ *				      crtcs
+ * @dev: DRM device
+ * @state: atomic state of DRM device
+ *
+ * This function calculates normalized zpos value for all modified planes in
+ * the provided atomic state of DRM device. For more information, see
+ * drm_atomic_helper_crtc_normalize_zpos() function.
+ *
+ * RETURNS
+ * Zero for success or -errno
+ */
+int drm_atomic_helper_normalize_zpos(struct drm_device *dev,
+				     struct drm_atomic_state *state)
+{
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+	struct drm_plane *plane;
+	struct drm_plane_state *plane_state;
+	int i, ret = 0;
+
+	for_each_plane_in_state(state, plane, plane_state, i) {
+		crtc = plane_state->crtc;
+		if (!crtc)
+			continue;
+		if (plane->state->zpos != plane_state->zpos) {
+			crtc_state =
+				drm_atomic_get_existing_crtc_state(state, crtc);
+			crtc_state->zpos_changed = true;
+		}
+	}
+
+	for_each_crtc_in_state(state, crtc, crtc_state, i) {
+		if (crtc_state->plane_mask != crtc->state->plane_mask ||
+		    crtc_state->zpos_changed) {
+			ret = drm_atomic_helper_crtc_normalize_zpos(crtc,
+								    crtc_state);
+			if (ret)
+				return ret;
+		}
+	}
+	return 0;
+}

drivers/gpu/drm/drm_crtc_internal.h

@@ -128,3 +128,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 
 int drm_modeset_register_all(struct drm_device *dev);
 void drm_modeset_unregister_all(struct drm_device *dev);
+
+/* drm_blend.c */
+int drm_atomic_helper_normalize_zpos(struct drm_device *dev,
+				     struct drm_atomic_state *state);

include/drm/drm_crtc.h

@@ -308,6 +308,7 @@ struct drm_plane_helper_funcs;
  * @mode_changed: crtc_state->mode or crtc_state->enable has been changed
  * @active_changed: crtc_state->active has been toggled.
  * @connectors_changed: connectors to this crtc have been updated
+ * @zpos_changed: zpos values of planes on this crtc have been updated
  * @color_mgmt_changed: color management properties have changed (degamma or
  *	gamma LUT or CSC matrix)
  * @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes
@@ -344,6 +345,7 @@ struct drm_crtc_state {
 	bool mode_changed : 1;
 	bool active_changed : 1;
 	bool connectors_changed : 1;
+	bool zpos_changed : 1;
 	bool color_mgmt_changed : 1;
 
 	/* attached planes bitmask:
@@ -1409,6 +1411,9 @@ struct drm_connector {
  * @src_w: width of visible portion of plane (in 16.16)
  * @src_h: height of visible portion of plane (in 16.16)
  * @rotation: rotation of the plane
+ * @zpos: priority of the given plane on crtc (optional)
+ * @normalized_zpos: normalized value of zpos: unique, range from 0 to N-1
+ *	where N is the number of active planes for given crtc
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_plane_state {
@@ -1429,6 +1434,10 @@ struct drm_plane_state {
 	/* Plane rotation */
 	unsigned int rotation;
 
+	/* Plane zpos */
+	unsigned int zpos;
+	unsigned int normalized_zpos;
+
 	struct drm_atomic_state *state;
 };
 
@@ -1688,6 +1697,7 @@ enum drm_plane_type {
  * @properties: property tracking for this plane
  * @type: type of plane (overlay, primary, cursor)
  * @state: current atomic state for this plane
+ * @zpos_property: zpos property for this plane
  * @helper_private: mid-layer private data
  */
 struct drm_plane {
@@ -1732,6 +1742,8 @@ struct drm_plane {
 	const struct drm_plane_helper_funcs *helper_private;
 
 	struct drm_plane_state *state;
+
+	struct drm_property *zpos_property;
 };
 
 /**
@@ -2958,6 +2970,14 @@ extern void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
 				       uint degamma_lut_size,
 				       bool has_ctm,
 				       uint gamma_lut_size);
+
+int drm_plane_create_zpos_property(struct drm_plane *plane,
+				   unsigned int zpos,
+				   unsigned int min, unsigned int max);
+
+int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
+					     unsigned int zpos);
+
 /* Helpers */
 struct drm_mode_object *drm_mode_object_find(struct drm_device *dev,
 					     uint32_t id, uint32_t type);