Re: [PATCH v3 1/3] drm: add generic zpos property

Hello,

On 2016-01-14 11:46, Ville Syrjälä wrote:

On Tue, Jan 12, 2016 at 02:39:18PM +0100, Marek Szyprowski wrote:

...

This patch adds support for generic plane's zpos property property with well-defined semantics:

• added zpos properties to drm core 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

Documentation/DocBook/gpu.tmpl | 14 ++++- drivers/gpu/drm/drm_atomic.c | 4 ++ drivers/gpu/drm/drm_atomic_helper.c | 116 ++++++++++++++++++++++++++++++++++++ drivers/gpu/drm/drm_crtc.c | 53 ++++++++++++++++ include/drm/drm_crtc.h | 14 +++++ 5 files changed, 199 insertions(+), 2 deletions(-)

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl index 6c6e81a9eaf4..f6b7236141b6 100644 --- a/Documentation/DocBook/gpu.tmpl +++ b/Documentation/DocBook/gpu.tmpl @@ -2004,7 +2004,7 @@ void intel_crt_init(struct drm_device *dev)

<td valign="top" >Description/Restrictions</td> </tr> <tr> - <td rowspan="37" valign="top" >DRM</td> + <td rowspan="38" valign="top" >DRM</td> <td valign="top" >Generic</td> <td valign="top" >“rotation”</td> <td valign="top" >BITMASK</td> @@ -2256,7 +2256,7 @@ void intel_crt_init(struct drm_device *dev) <td valign="top" >property to suggest an Y offset for a connector</td> </tr> <tr> - <td rowspan="3" valign="top" >Optional</td> + <td rowspan="4" valign="top" >Optional</td> <td valign="top" >“scaling mode”</td> <td valign="top" >ENUM</td> <td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td> @@ -2280,6 +2280,16 @@ void intel_crt_init(struct drm_device *dev) <td valign="top" >TBD</td> </tr> <tr> + <td valign="top" > "zpos" </td> + <td valign="top" >RANGE</td> + <td valign="top" >Min=0, Max=255</td> + <td valign="top" >Plane</td> + <td valign="top" >Plane's 'z' position during blending (0 for background, 255 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.</td>

I don't think this is going to work very well. Mixing the same range of 0-255 for all planes, with potentially some of them being IMMUTABLE for sure won't end well, or at least won't allow userspace to see if there are any constraints between the zpos of the planes.

So I think what we should do is let the driver specify the valid range, and get rid of the obj id based conflict resolution in favor of just rejecting conflicts outright. In cases where you can't move the planes between crtcs, the driver ought to specify the range based on the number of planes present on the crtc. If planes can be moved betweens crtcs the range obviously needs to be larger to accomodate all the possible planes on the crtc.

Eg. on Intel VLV/CHV we could have the following setup: primary zpos 0-2 sprite 0 zpos 0-2 sprite 1 zpos 0-2 cursor zpos 3

That makes it very clear the curso is always on top, and the other planes can be rearranged more or less freely. These planes can't be moved between crtcs, so each there's an identical set of planes for each crtc.

On old Intel hw (gen2/3) we could have something like: plane A zpos 0-3 plane B zpos 0-3 plane C zpos 0-3 overlay zpos 0-3 cursor B zpos 4 cursor A zpos 5

Most of these planes can be moved between crtcs, and IIRC there are probably more constraints on exactly how they can be stacked, but this is at least fairly close to the truth. Again the cursors are always on top, and in this case the order between the two cursor planes is also fixed.

I wasn't aware of a hardware, which has limited configuration of zpos only to some planes. I thought only about 2 cases: either completely configurable planes arrangement, or planes fixed to some hw dependent order. I see no problem to let drivers to define their own limits for mutable zpos property.

Now the question is weather we should allow to set the non-zero minimal value for mutable zpos? I can imagine that there might be a hardware, which has fixed background plane and a few configurable overlay planes. I assume that in such case, the calculated normalized_zpos should still start from zero.

I did originally have the same obj id based sorting idea (and even posted some kind of a patch for it IIRC) but that was before atomic existed, so there was a real need to allow reordering the planes with just a single setplane ioctl call. With atomic I don't see any real benefit from it the obj id based sorting, and as I've noted there are definitely downsides to it.

What are the downsides of using obj id as additional sorting criteria? It solves all the ambiguities and simplifies checks (there is no need to check if there are 2 planes of the same zpos value).

...

• </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/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 6a21e5c378c1..97bb069cb6a3 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -614,6 +614,8 @@ 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 == config->zpos_property) {

• state->zpos = val;
  

  } else if (plane->funcs->atomic_set_property) { return plane->funcs->atomic_set_property(plane, state, property, val);

@@ -670,6 +672,8 @@ 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 == config->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 d0d4b2ff7c21..257946fac94b 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -31,6 +31,7 @@ #include <drm/drm_crtc_helper.h> #include <drm/drm_atomic_helper.h> #include <linux/fence.h> +#include <linux/sort.h>

/**

• DOC: overview

@@ -507,6 +508,117 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, } EXPORT_SYMBOL(drm_atomic_helper_check_modeset);

+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;
• int zpos_a = (sa->zpos << 16) + sa->plane->base.id;
• int zpos_b = (sb->zpos << 16) + sb->plane->base.id;
• return zpos_a - zpos_b;

+}

+/**

• • 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 uniqe
• • 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, n = 0;
• int ret = 0;
• DRM_DEBUG_ATOMIC("[CRTC:%d:%s] calculating normalized zpos values\n",

• 	 crtc->base.id, crtc->name);
  

• states = kmalloc(total_planes * sizeof(*states), GFP_KERNEL);
• 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 fail;
  

• }
  

• 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);
  

• }

+fail:

• kfree(states);
• return ret;

+} +EXPORT_SYMBOL(drm_atomic_helper_crtc_normalize_zpos);

+static 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;
• /*

• * If zpos_property is not initialized, then it makes no sense
  

• * to calculate normalized zpos values.
  

• */
  

• if (!dev->mode_config.zpos_property)

• return 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;

+}

• /**
  • drm_atomic_helper_check_planes - validate state object for planes changes
  • @dev: DRM device

@@ -532,6 +644,10 @@ 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_crtc.c b/drivers/gpu/drm/drm_crtc.c index 62fa95fa5471..54a21e7c1ca5 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -5880,6 +5880,59 @@ struct drm_property *drm_mode_create_rotation_property(struct drm_device *dev, EXPORT_SYMBOL(drm_mode_create_rotation_property);

/**

• • drm_mode_create_zpos_property - create muttable zpos property
• • @dev: DRM device
• • This function initializes generic muttable 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.
• • Drivers can also use drm_atomic_helper_normalize_zpos() function to calculate
• • drm_plane_state->normalized_zpos values.
• • Returns:
• • Zero on success, negative errno on failure.
• */

+int drm_mode_create_zpos_property(struct drm_device *dev) +{

• struct drm_property *prop;
• prop = drm_property_create_range(dev, 0, "zpos", 0, 255);
• if (!prop)

• return -ENOMEM;
  

• dev->mode_config.zpos_property = prop;
• return 0;

+} +EXPORT_SYMBOL(drm_mode_create_zpos_property);

+/**

• • drm_plane_create_zpos_property - create immuttable zpos property
• • @dev: DRM device
• • This function initializes generic immuttable 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_mode_create_zpos_immutable_property(struct drm_device *dev) +{

• struct drm_property *prop;
• prop = drm_property_create_range(dev, DRM_MODE_PROP_IMMUTABLE, "zpos",

• 			 0, 255);
  

• if (!prop)

• return -ENOMEM;
  

• dev->mode_config.zpos_immutable_property = prop;
• return 0;

+} +EXPORT_SYMBOL(drm_mode_create_zpos_immutable_property);

+/**

• DOC: Tile group
• Tile groups are used to represent tiled monitors with a unique

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 3b040b355472..0607ad2ce918 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -305,6 +305,7 @@ 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
  • @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes
  • @last_vblank_count: for helpers and drivers to capture the vblank of the
  • update to ensure framebuffer cleanup isn't done too early

@@ -331,6 +332,7 @@ struct drm_crtc_state { bool mode_changed : 1; bool active_changed : 1; bool connectors_changed : 1;

• bool zpos_changed : 1;

  /* attached planes bitmask:

  • WARNING: transitional helpers do not maintain plane_mask so

@@ -1243,6 +1245,9 @@ struct drm_connector {

• plane (in 16.16)
• @src_w: width of visible portion of plane (in 16.16)
• @src_h: height of visible portion of plane (in 16.16)

• • @zpos: priority of the given plane on crtc (optional)
• • @normalized_zpos: normalized value of zpos: uniqe, range from 0 to
• • (number of planes - 1) for given crtc
  • @state: backpointer to global drm_atomic_state
  */ struct drm_plane_state {

@@ -1263,6 +1268,10 @@ struct drm_plane_state { /* Plane rotation */ unsigned int rotation;

• /* Plane zpos */
• unsigned int zpos;
• unsigned int normalized_zpos;
• struct drm_atomic_state *state; };

@@ -2083,6 +2092,8 @@ struct drm_mode_config { struct drm_property *tile_property; struct drm_property *plane_type_property; struct drm_property *rotation_property;

• struct drm_property *zpos_property;
• struct drm_property *zpos_immutable_property; struct drm_property *prop_src_x; struct drm_property *prop_src_y; struct drm_property *prop_src_w;

@@ -2484,6 +2495,9 @@ extern struct drm_property *drm_mode_create_rotation_property(struct drm_device extern unsigned int drm_rotation_simplify(unsigned int rotation, unsigned int supported_rotations);

+extern int drm_mode_create_zpos_property(struct drm_device *dev); +extern int drm_mode_create_zpos_immutable_property(struct drm_device *dev);

• /* Helpers */

  static inline struct drm_plane *drm_plane_find(struct drm_device *dev,

-- 1.9.2

Best regards