diff mbox

[v4,1/4] drm: add generic zpos property

Message ID 1465809686-22507-2-git-send-email-benjamin.gaignard@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Benjamin Gaignard June 13, 2016, 9:21 a.m. UTC
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>

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/DocBook/gpu.tmpl      |  10 ++
 drivers/gpu/drm/Makefile            |   2 +-
 drivers/gpu/drm/drm_atomic.c        |   4 +
 drivers/gpu/drm/drm_atomic_helper.c |   6 +
 drivers/gpu/drm/drm_blend.c         | 230 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_crtc_internal.h |   3 +
 include/drm/drm_crtc.h              |  30 +++++
 7 files changed, 284 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/drm_blend.c

Comments

Laurent Pinchart June 21, 2016, 11:45 p.m. UTC | #1
Hi Benjamin,

Thank you for the patch.

Could you please reply to Ville's comment to v1 of this patch (posted on April 
the 25th) ?

Please also see below for additional comments.

On Monday 13 Jun 2016 11:21:23 Benjamin Gaignard wrote:
> 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>
> 
> 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/DocBook/gpu.tmpl      |  10 ++
>  drivers/gpu/drm/Makefile            |   2 +-
>  drivers/gpu/drm/drm_atomic.c        |   4 +
>  drivers/gpu/drm/drm_atomic_helper.c |   6 +
>  drivers/gpu/drm/drm_blend.c         | 230 +++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_crtc_internal.h |   3 +
>  include/drm/drm_crtc.h              |  30 +++++
>  7 files changed, 284 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/drm_blend.c

[snip]

> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> new file mode 100644
> index 0000000..9a5361a
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_blend.c
> @@ -0,0 +1,230 @@

[snip]

> +/**
> + * 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
> + */
> +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, zpos, 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, zpos = 0; i < n; i++, zpos++) {
> +		plane = states[i]->plane;
> +
> +		zpos = max_t(int, zpos, states[i]->zpos);
> +
> +		WARN_ON(zpos > plane->zpos_property->values[1]);

This crashes if the plane doesn't have a zpos property. The simplest fix is to 
write the check as

		WARN_ON(plane->zpos_property &&
			zpos > plane->zpos_property->values[1]);

but I wonder how we should handle drivers that instantiate a zpos property for 
a subdev of the planes only. For drivers that don't use zpos at all you could 
maybe avoid calling this function.

Additionally, this check is triggered with the rcar-du-drm driver when 
performing the following operations:

- Perform a mode set with the CRTC primary plane only (that plane doesn't have 
a zpos property)

- Add 7 overlay planes with zpos values 1 to 7 (their zpos property range is 
1-7)

- Modify the zpos value of all overlay planes one by one to 7 to 1 (setting 
zpos 7 for plane 1 first, then zpos 6 for plane 2, ...)

I get normalized zpos values such as

[   84.892927] [PLANE:39:plane-8] normalized zpos value 9
[   85.899284] [PLANE:25:plane-0] normalized zpos value 0
[   85.904488] [PLANE:37:plane-7] normalized zpos value 2
[   85.909633] [PLANE:35:plane-6] normalized zpos value 3
[   85.914793] [PLANE:33:plane-5] normalized zpos value 4
[   85.919936] [PLANE:31:plane-4] normalized zpos value 5
[   85.925100] [PLANE:29:plane-3] normalized zpos value 6
[   85.930245] [PLANE:27:plane-2] normalized zpos value 7

(plane 25 is the primary plane, all other planes are the overlay planes, added 
in the order 27, 29, 31, 33, 35, 37, 37 in the sequence above)

> +		states[i]->normalized_zpos = zpos;
> +		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] normalized zpos value %d\n",
> +				 plane->base.id, plane->name, zpos);
> +	}
> +	crtc_state->zpos_changed = true;
> +
> +done:
> +	kfree(states);
> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_atomic_helper_crtc_normalize_zpos);
> +
> +/**
> + * 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;
> +}
> +EXPORT_SYMBOL(drm_atomic_helper_normalize_zpos);
Benjamin Gaignard June 23, 2016, 12:51 p.m. UTC | #2
2016-06-22 1:45 GMT+02:00 Laurent Pinchart <laurent.pinchart@ideasonboard.com>:
> Hi Benjamin,
>
> Thank you for the patch.
>
> Could you please reply to Ville's comment to v1 of this patch (posted on April
> the 25th) ?
>

For each iteration of the patches we have swap between two solutions:
- have normalization done between 0 to N-1 without taking care of zpos
property range
- take care of zpos property range while computing normalized zpos

First the solution is the most simple and the more robust so I will
definitively go for it.

[snip]
>> +     sort(states, n, sizeof(*states), drm_atomic_state_zpos_cmp, NULL);
>> +
>> +     for (i = 0, zpos = 0; i < n; i++, zpos++) {
>> +             plane = states[i]->plane;
>> +
>> +             zpos = max_t(int, zpos, states[i]->zpos);
>> +
>> +             WARN_ON(zpos > plane->zpos_property->values[1]);
>
> This crashes if the plane doesn't have a zpos property. The simplest fix is to
> write the check as
>
>                 WARN_ON(plane->zpos_property &&
>                         zpos > plane->zpos_property->values[1]);

Thanks I will add that in v5

> but I wonder how we should handle drivers that instantiate a zpos property for
> a subdev of the planes only. For drivers that don't use zpos at all you could
> maybe avoid calling this function.
>

I think it will be difficult to mix planes with and without zpos property.
My suggestion is to use immutable zpos property for primary and cursor plane.
drm_atomic_helper_crtc_normalize_zpos() is only called if plane zpos
value change
so if driver don't use it normalization will not be done.

> Additionally, this check is triggered with the rcar-du-drm driver when
> performing the following operations:
>
> - Perform a mode set with the CRTC primary plane only (that plane doesn't have
> a zpos property)
>
> - Add 7 overlay planes with zpos values 1 to 7 (their zpos property range is
> 1-7)
>
> - Modify the zpos value of all overlay planes one by one to 7 to 1 (setting
> zpos 7 for plane 1 first, then zpos 6 for plane 2, ...)
>
> I get normalized zpos values such as
>
> [   84.892927] [PLANE:39:plane-8] normalized zpos value 9
> [   85.899284] [PLANE:25:plane-0] normalized zpos value 0
> [   85.904488] [PLANE:37:plane-7] normalized zpos value 2
> [   85.909633] [PLANE:35:plane-6] normalized zpos value 3
> [   85.914793] [PLANE:33:plane-5] normalized zpos value 4
> [   85.919936] [PLANE:31:plane-4] normalized zpos value 5
> [   85.925100] [PLANE:29:plane-3] normalized zpos value 6
> [   85.930245] [PLANE:27:plane-2] normalized zpos value 7
>
> (plane 25 is the primary plane, all other planes are the overlay planes, added
> in the order 27, 29, 31, 33, 35, 37, 37 in the sequence above)
>
I'm not able to reproduce you problem on my setup with one primary and
two overlay.
When back to 0 to N-1 normalization algo you should see the problem anymore

[snip]
> --
> Regards,
>
> Laurent Pinchart
>
diff mbox

Patch

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
index dac18b4..8baac27 100644
--- a/Documentation/DocBook/gpu.tmpl
+++ b/Documentation/DocBook/gpu.tmpl
@@ -2146,6 +2146,16 @@  void intel_crt_init(struct drm_device *dev)
 		the underlying hardware).</td>
 	</tr>
 	<tr>
+	<td valign="top" > "zpos" </td>
+	<td valign="top" >RANGE</td>
+	<td valign="top" >Min= driver dependent, Max= driver dependent</td>
+	<td valign="top" >Plane</td>
+	<td valign="top" >Plane's 'z' position during blending operation (0 for background, highest for frontmost).
+		If two planes assigned to same CRTC have equal zpos values, the plane with higher plane
+		id is treated as closer to front. Can be IMMUTABLE if driver doesn't support changing
+		planes' order. Exact value range is driver dependent.</td>
+	</tr>
+	<tr>
 	<td rowspan="20" valign="top" >i915</td>
 	<td rowspan="2" valign="top" >Generic</td>
 	<td valign="top" >"Broadcast RGB"</td>
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index be43afb..dbec0ea 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -2,7 +2,7 @@ 
 # Makefile for the drm device driver.  This driver provides support for the
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
-drm-y       :=	drm_auth.o drm_bufs.o drm_cache.o \
+drm-y       :=	drm_auth.o drm_bufs.o drm_blend.o drm_cache.o \
 		drm_context.o drm_dma.o \
 		drm_fops.o drm_gem.o drm_ioctl.o drm_irq.o \
 		drm_lock.o drm_memory.o drm_drv.o drm_vm.o \
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5e4b820..812b0f0 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -690,6 +690,8 @@  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);
@@ -746,6 +748,8 @@  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 {
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index bb98d74..9fbe08c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/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;
 
diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
new file mode 100644
index 0000000..9a5361a
--- /dev/null
+++ b/drivers/gpu/drm/drm_blend.c
@@ -0,0 +1,230 @@ 
+/*
+ * 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
+ * @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 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, min);
+
+	plane->zpos_property = prop;
+	return 0;
+}
+EXPORT_SYMBOL(drm_plane_create_zpos_property);
+
+/**
+ * drm_plane_create_zpos_immutable_property - create immuttable zpos property
+ * @plane: drm plane
+ * @min: minimal possible value of zpos property
+ * @max: maximal possible 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 min, unsigned int max)
+{
+	struct drm_property *prop;
+
+	prop = drm_property_create_range(plane->dev, DRM_MODE_PROP_IMMUTABLE,
+					 "zpos", min, max);
+	if (!prop)
+		return -ENOMEM;
+
+	drm_object_attach_property(&plane->base, prop, min);
+
+	plane->zpos_property = prop;
+	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
+ */
+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, zpos, 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, zpos = 0; i < n; i++, zpos++) {
+		plane = states[i]->plane;
+
+		zpos = max_t(int, zpos, states[i]->zpos);
+
+		WARN_ON(zpos > plane->zpos_property->values[1]);
+		states[i]->normalized_zpos = zpos;
+		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] normalized zpos value %d\n",
+				 plane->base.id, plane->name, zpos);
+	}
+	crtc_state->zpos_changed = true;
+
+done:
+	kfree(states);
+	return ret;
+}
+EXPORT_SYMBOL(drm_atomic_helper_crtc_normalize_zpos);
+
+/**
+ * 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;
+}
+EXPORT_SYMBOL(drm_atomic_helper_normalize_zpos);
diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
index a78c138..37d9068 100644
--- a/drivers/gpu/drm/drm_crtc_internal.h
+++ b/drivers/gpu/drm/drm_crtc_internal.h
@@ -42,3 +42,6 @@  int drm_atomic_get_property(struct drm_mode_object *obj,
 int drm_mode_atomic_ioctl(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv);
 
+/* drm_blend.c */
+int drm_atomic_helper_normalize_zpos(struct drm_device *dev,
+				     struct drm_atomic_state *state);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 1a8d66c..11372e3 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -307,6 +307,7 @@  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
@@ -343,6 +344,7 @@  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:
@@ -1291,6 +1293,9 @@  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
+ *	 for given crtc
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_plane_state {
@@ -1311,6 +1316,10 @@  struct drm_plane_state {
 	/* Plane rotation */
 	unsigned int rotation;
 
+	/* Plane zpos */
+	unsigned int zpos;
+	unsigned int normalized_zpos;
+
 	struct drm_atomic_state *state;
 };
 
@@ -1545,6 +1554,7 @@  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 {
@@ -1586,6 +1596,8 @@  struct drm_plane {
 	const struct drm_plane_helper_funcs *helper_private;
 
 	struct drm_plane_state *state;
+
+	struct drm_property *zpos_property;
 };
 
 /**
@@ -2662,6 +2674,24 @@  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_atomic_set_zpos_property(struct drm_plane *plane,
+				       struct drm_plane_state *state,
+				       struct drm_property *property,
+				       uint64_t val);
+
+int drm_plane_atomic_get_zpos_property(struct drm_plane *plane,
+				       const struct drm_plane_state *state,
+				       struct drm_property *property,
+				       uint64_t *val);
+
+int drm_plane_create_zpos_property(struct drm_plane *plane,
+				   unsigned int min, unsigned int max);
+
+int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
+					     unsigned int min,
+					     unsigned int max);
+
 /* Helpers */
 
 static inline struct drm_plane *drm_plane_find(struct drm_device *dev,