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>

5 files changed, 89 insertions, 28 deletions

diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
index bed775ff81..d4df0dc66e 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
@@ -181,24 +181,41 @@ void QEglFSKmsGbmScreen::flip()
 
     FrameBuffer *fb = framebufferForBufferObject(m_gbm_bo_next);
 
-    if (!output().mode_set) {
-        int ret = drmModeSetCrtc(device()->fd(),
-                                 output().crtc_id,
+    QEglFSKmsOutput &op(output());
+    const int fd = device()->fd();
+    const uint32_t w = op.modes[op.mode].hdisplay;
+    const uint32_t h = op.modes[op.mode].vdisplay;
+
+    if (!op.mode_set) {
+        int ret = drmModeSetCrtc(fd,
+                                 op.crtc_id,
                                  fb->fb,
                                  0, 0,
-                                 &output().connector_id, 1,
-                                 &output().modes[output().mode]);
+                                 &op.connector_id, 1,
+                                 &op.modes[op.mode]);
 
-        if (ret) {
-            qErrnoWarning("Could not set DRM mode!");
+        if (ret == -1) {
+            qErrnoWarning(errno, "Could not set DRM mode!");
         } else {
-            output().mode_set = true;
+            op.mode_set = true;
             setPowerState(PowerStateOn);
+
+            if (!op.plane_set) {
+                op.plane_set = true;
+                if (op.wants_plane) {
+                    int ret = drmModeSetPlane(fd, op.plane_id, op.crtc_id,
+                                              uint32_t(-1), 0,
+                                              0, 0, w, h,
+                                              0 << 16, 0 << 16, w << 16, h << 16);
+                    if (ret == -1)
+                        qErrnoWarning(errno, "drmModeSetPlane failed");
+                }
+            }
         }
     }
 
-    int ret = drmModePageFlip(device()->fd(),
-                              output().crtc_id,
+    int ret = drmModePageFlip(fd,
+                              op.crtc_id,
                               fb->fb,
                               DRM_MODE_PAGE_FLIP_EVENT,
                               this);
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]);
         }
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldevicescreen.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldevicescreen.cpp
index 1f672afeb4..3935c99b9e 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldevicescreen.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_egldevice/qeglfskmsegldevicescreen.cpp
@@ -67,13 +67,16 @@ QPlatformCursor *QEglFSKmsEglDeviceScreen::cursor() const
 
 void QEglFSKmsEglDeviceScreen::waitForFlip()
 {
-    if (!output().mode_set) {
-        output().mode_set = true;
+    QEglFSKmsOutput &op(output());
+    const int fd = device()->fd();
+    const uint32_t w = op.modes[op.mode].hdisplay;
+    const uint32_t h = op.modes[op.mode].vdisplay;
 
-        drmModeCrtcPtr currentMode = drmModeGetCrtc(device()->fd(), output().crtc_id);
-        const bool alreadySet = currentMode
-            && currentMode->width == output().modes[output().mode].hdisplay
-            && currentMode->height == output().modes[output().mode].vdisplay;
+    if (!op.mode_set) {
+        op.mode_set = true;
+
+        drmModeCrtcPtr currentMode = drmModeGetCrtc(fd, op.crtc_id);
+        const bool alreadySet = currentMode && currentMode->width == w && currentMode->height == h;
         if (currentMode)
             drmModeFreeCrtc(currentMode);
         if (alreadySet) {
@@ -87,14 +90,26 @@ void QEglFSKmsEglDeviceScreen::waitForFlip()
         }
 
         qCDebug(qLcEglfsKmsDebug, "Setting mode");
-        int ret = drmModeSetCrtc(device()->fd(), output().crtc_id,
+        int ret = drmModeSetCrtc(fd, op.crtc_id,
                                  uint32_t(-1), 0, 0,
-                                 &output().connector_id, 1,
-                                 &output().modes[output().mode]);
+                                 &op.connector_id, 1,
+                                 &op.modes[op.mode]);
         if (ret)
-            qFatal("drmModeSetCrtc failed");
+            qErrnoWarning(errno, "drmModeSetCrtc failed");
     }
 
+    if (!op.plane_set) {
+        op.plane_set = true;
+
+        if (op.wants_plane) {
+            qCDebug(qLcEglfsKmsDebug, "Setting plane %u", op.plane_id);
+            int ret = drmModeSetPlane(fd, op.plane_id, op.crtc_id, uint32_t(-1), 0,
+                                      0, 0, w, h,
+                                      0 << 16, 0 << 16, w << 16, h << 16);
+            if (ret == -1)
+                qErrnoWarning(errno, "drmModeSetPlane failed");
+        }
+    }
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsdevice.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsdevice.cpp
index b3c1fbb1bd..75dd083750 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsdevice.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsdevice.cpp
@@ -329,9 +329,32 @@ QEglFSKmsScreen *QEglFSKmsDevice::createScreenForConnector(drmModeResPtr resourc
         drmModeGetCrtc(m_dri_fd, crtc_id),
         modes,
         connector->subpixel,
-        connectorProperty(connector, QByteArrayLiteral("DPMS"))
+        connectorProperty(connector, QByteArrayLiteral("DPMS")),
+        false,
+        0,
+        false
     };
 
+    bool ok;
+    int idx = qEnvironmentVariableIntValue("QT_QPA_EGLFS_KMS_PLANE_INDEX", &ok);
+    if (ok) {
+        drmModePlaneRes *planeResources = drmModeGetPlaneResources(m_dri_fd);
+        if (planeResources) {
+            if (idx >= 0 && idx < int(planeResources->count_planes)) {
+                drmModePlane *plane = drmModeGetPlane(m_dri_fd, planeResources->planes[idx]);
+                if (plane) {
+                    output.wants_plane = true;
+                    output.plane_id = plane->plane_id;
+                    qCDebug(qLcEglfsKmsDebug, "Forcing plane index %d, plane id %u (belongs to crtc id %u)",
+                            idx, plane->plane_id, plane->crtc_id);
+                    drmModeFreePlane(plane);
+                }
+            } else {
+                qWarning("Invalid plane index %d, must be between 0 and %u", idx, planeResources->count_planes - 1);
+            }
+        }
+    }
+
     m_crtc_allocator |= (1 << output.crtc_id);
     m_connector_allocator |= (1 << output.connector_id);
 
@@ -406,7 +429,7 @@ void QEglFSKmsDevice::createScreens()
         if (idx >= 0 && idx < resources->count_connectors)
             wantedConnectorIndex = idx;
         else
-            qWarning("Invalid connector index %d", idx);
+            qWarning("Invalid connector index %d, must be between 0 and %u", idx, resources->count_connectors - 1);
     }
 
     for (int i = 0; i < resources->count_connectors; i++) {
diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h
index 2b6a0ffe6c..fa331f0931 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h
@@ -67,6 +67,9 @@ struct QEglFSKmsOutput
     QList<drmModeModeInfo> modes;
     int subpixel;
     drmModePropertyPtr dpms_prop;
+    bool wants_plane;
+    uint32_t plane_id;
+    bool plane_set;
 };
 
 class Q_EGLFS_EXPORT QEglFSKmsScreen : public QEglFSScreen