eglfs: allow forcing an overlay plane

Add a QT_QPA_EGLFS_KMS_PLANE_INDEX environment variable that applies
both to the GBM and EGLDevice backends. When set to a value between 0 and
the number of planes on the connector - 1, the chosen overlay plane will
be used for output, meaning there will be a drmModeSetPlane to configure,
and, in case of EGLDevice, the plane's corresponding EGL layer will get
chosen instead of the CRTC's.

Task-number: QTBUG-57386
Change-Id: I12c89472ea5730987052f39211fadc597d1302ef
Reviewed-by: Pasi Petäjäjärvi <pasi.petajajarvi@qt.io>

1 files changed, 9 insertions, 6 deletions

diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
index b443a724ec..cf1de71831 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldeviceintegration.cpp
@@ -39,11 +39,11 @@
 ****************************************************************************/
 
 #include "qeglfskmsegldeviceintegration.h"
+#include "qeglfskmsegldevice.h"
+#include "qeglfskmsegldevicescreen.h"
 #include <QtEglSupport/private/qeglconvenience_p.h>
 #include "private/qeglfswindow_p.h"
 #include "private/qeglfscursor_p.h"
-#include "qeglfskmsegldevice.h"
-#include "qeglfskmsscreen.h"
 #include <QLoggingCategory>
 #include <private/qmath_p.h>
 
@@ -171,20 +171,23 @@ void QEglJetsonTK1Window::resetSurface()
         return;
     }
 
-    QEglFSKmsScreen *cur_screen = static_cast<QEglFSKmsScreen*>(screen());
+    QEglFSKmsEglDeviceScreen *cur_screen = static_cast<QEglFSKmsEglDeviceScreen *>(screen());
     Q_ASSERT(cur_screen);
-    qCDebug(qLcEglfsKmsDebug, "Searching for id: %d", cur_screen->output().crtc_id);
+    QEglFSKmsOutput &output(cur_screen->output());
+    const uint32_t wantedId = !output.wants_plane ? output.crtc_id : output.plane_id;
+    qCDebug(qLcEglfsKmsDebug, "Searching for id: %d", wantedId);
 
     EGLOutputLayerEXT layer = EGL_NO_OUTPUT_LAYER_EXT;
     for (int i = 0; i < actualCount; ++i) {
         EGLAttrib id;
         if (m_integration->m_funcs->query_output_layer_attrib(display, layers[i], EGL_DRM_CRTC_EXT, &id)) {
             qCDebug(qLcEglfsKmsDebug, "  [%d] layer %p - crtc %d", i, layers[i], (int) id);
-            if (id == EGLAttrib(cur_screen->output().crtc_id))
+            if (id == EGLAttrib(wantedId))
                 layer = layers[i];
         } else if (m_integration->m_funcs->query_output_layer_attrib(display, layers[i], EGL_DRM_PLANE_EXT, &id)) {
-            // Not used yet, just for debugging.
             qCDebug(qLcEglfsKmsDebug, "  [%d] layer %p - plane %d", i, layers[i], (int) id);
+            if (id == EGLAttrib(wantedId))
+                layer = layers[i];
         } else {
             qCDebug(qLcEglfsKmsDebug, "  [%d] layer %p - unknown", i, layers[i]);
         }