eglfs/kms: Add drm atomic zpos property handling

This adds the ability to specify a ZPOS property for the eglfs plane
ZPOS will allow to control the relative position between eglfs layer
and the other layers.

It is bound to using QT_QPA_EGLFS_KMS_ZPOS environment variable to determine
its value.

Change-Id: I51986ccb22a9dbaeef20165ac5feb7dbe8047373
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

3 files changed, 7 insertions, 0 deletions

diff --git a/src/platformsupport/kmsconvenience/qkmsdevice.cpp b/src/platformsupport/kmsconvenience/qkmsdevice.cpp
index d477d12d72..71422b469b 100644
--- a/src/platformsupport/kmsconvenience/qkmsdevice.cpp
+++ b/src/platformsupport/kmsconvenience/qkmsdevice.cpp
@@ -824,6 +824,8 @@ void QKmsDevice::discoverPlanes()
                 plane.crtcXPropertyId = prop->prop_id;
             } else if (!strcasecmp(prop->name, "crtc_y")) {
                 plane.crtcYPropertyId = prop->prop_id;
+            } else if (!strcasecmp(prop->name, "zpos")) {
+                plane.zposPropertyId = prop->prop_id;
             }
         });
 
diff --git a/src/platformsupport/kmsconvenience/qkmsdevice_p.h b/src/platformsupport/kmsconvenience/qkmsdevice_p.h
index 5465cad941..403972fbb8 100644
--- a/src/platformsupport/kmsconvenience/qkmsdevice_p.h
+++ b/src/platformsupport/kmsconvenience/qkmsdevice_p.h
@@ -177,6 +177,7 @@ struct QKmsPlane
     uint32_t srcheightPropertyId = 0;
     uint32_t crtcwidthPropertyId = 0;
     uint32_t crtcheightPropertyId = 0;
+    uint32_t zposPropertyId = 0;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QKmsPlane::Rotations)
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
index c3151e1fd0..0cbb494c2f 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
@@ -311,6 +311,10 @@ void QEglFSKmsGbmScreen::flip()
                                      m_output.modes[m_output.mode].hdisplay);
             drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->crtcheightPropertyId,
                                      m_output.modes[m_output.mode].vdisplay);
+
+            static int zpos = qEnvironmentVariableIntValue("QT_QPA_EGLFS_KMS_ZPOS");
+            if (zpos)
+                drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->zposPropertyId, zpos);
         }
 #endif
     } else {