[PATCH v2 1/1] drm/vkms: add zpos plane property

[José Expósito]

Add support for the zpos plane property. Depending on the plane type:

 - Primary and cursor planes: Create an immutable zpos property. The
   primary plane is always at the bottom and the cursor plane is always
   on the top.
 - Overlay planes: Create a mutable zpos property allowing to change
   their order but always keep them between the primary and cursor
   planes.

As documented, "vkms_crtc_state.active_planes" must be sorted by zpos.
This is achieved by inserting them in the array at their
normalized_zpos index.

The following igt-gpu-tools tests were executed:

                    |     master branch     |      this  patch      |
                    | SUCCESS | SKIP | FAIL | SUCCESS | SKIP | FAIL |
 kms_atomic         |      10 |   02 |   00 |      09 |   02 |   01 |
 kms_plane          |      06 |   00 |   14 |      06 |   00 |   14 |
 kms_plane_cursor   |      09 |   45 |   00 |      09 |   45 |   00 |
 kms_plane_multiple |      01 |   23 |   00 |      01 |   23 |   00 |
 kms_writeback      |      04 |   00 |   00 |      04 |   00 |   00 |

Notice that there is one test failing in the kms_atomic row
(plane-immutable-zpos) but it is due to timeout capturing CRC.
This happens when the primary plane is disabled and the composer is not
able to find the "primary_composer" variable.
While the timeout bug needs to be fixed in a different series, the zpos
property works as expected.

Signed-off-by: José Expósito <jose.exposito89 at gmail.com>

---

v2:

 - Use number of planes constant introduced in "drm/vkms: add support
   for multiple overlay planes" v2

 - Add a test results in the commit message
---
 drivers/gpu/drm/vkms/vkms_crtc.c  |  3 +--
 drivers/gpu/drm/vkms/vkms_drv.c   |  1 +
 drivers/gpu/drm/vkms/vkms_plane.c | 23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 57bbd32e9beb..4f23488b15f3 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -207,7 +207,6 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
 		return -ENOMEM;
 	vkms_state->num_active_planes = i;
 
-	i = 0;
 	drm_for_each_plane_mask(plane, crtc->dev, crtc_state->plane_mask) {
 		plane_state = drm_atomic_get_existing_plane_state(crtc_state->state,
 								  plane);
@@ -215,7 +214,7 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
 		if (!plane_state->visible)
 			continue;
 
-		vkms_state->active_planes[i++] =
+		vkms_state->active_planes[plane_state->normalized_zpos] =
 			to_vkms_plane_state(plane_state);
 	}
 
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 0ffe5f0e33f7..d7ee64f5e339 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -153,6 +153,7 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
 	 * fbdev helpers. We have to go with 0, meaning "pick the default",
 	 * which ix XRGB8888 in all cases. */
 	dev->mode_config.preferred_depth = 0;
+	dev->mode_config.normalize_zpos = true;
 	dev->mode_config.helper_private = &vkms_mode_config_helpers;
 
 	return vkms_output_init(vkmsdev, 0);
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index 32409e15244b..55d22a6a401a 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -81,6 +81,8 @@ static void vkms_plane_reset(struct drm_plane *plane)
 	}
 
 	__drm_gem_reset_shadow_plane(plane, &vkms_state->base);
+	vkms_state->base.base.zpos = drm_plane_index(plane);
+	vkms_state->base.base.normalized_zpos = drm_plane_index(plane);
 }
 
 static const struct drm_plane_funcs vkms_plane_funcs = {
@@ -158,6 +160,22 @@ static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {
 	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
 };
 
+static int vkms_plane_create_zpos_property(struct vkms_plane *plane)
+{
+	int ret;
+	unsigned int zpos = drm_plane_index(&plane->base);
+
+	if (plane->base.type == DRM_PLANE_TYPE_OVERLAY) {
+		ret = drm_plane_create_zpos_property(&plane->base, zpos,
+						     1, NUM_OVERLAY_PLANES);
+	} else {
+		ret = drm_plane_create_zpos_immutable_property(&plane->base,
+							       zpos);
+	}
+
+	return ret;
+}
+
 struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
 				   enum drm_plane_type type, int index)
 {
@@ -166,6 +184,7 @@ struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
 	struct vkms_plane *plane;
 	const u32 *formats;
 	int nformats;
+	int ret;
 
 	switch (type) {
 	case DRM_PLANE_TYPE_PRIMARY:
@@ -195,5 +214,9 @@ struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
 
 	drm_plane_helper_add(&plane->base, funcs);
 
+	ret = vkms_plane_create_zpos_property(plane);
+	if (ret)
+		return ERR_PTR(ret);
+
 	return plane;
 }
-- 
2.25.1