Add a tech preview eglfs device integration for VSP2 composition

This creates a new device integration for eglfs, eglfs_kms_vsp2, that's very
similar to eglfs_kms_gbm, but includes an extra step for doing VSP2 hardware
compositing.

The main Qt content is drawn to double buffered off-screen GBM buffers which
are converted using drmPrimeHandleToFD so we get DMA buffer file descriptors
that can be used by the VSP2 blending hardware. The blending hardware writes to
double buffered DRM dumb buffers, which are flipped with drmModePageFlip.

Communicating with the VSP2 is done using the Video4Linux2 (V4L2) streaming
API. There are two steps in creating abstractions for this. First, there is the
QLinuxMedia class that consists of a Qt style wrapper for V4L2 without anything
VSP2 specific. Second, there is QVsp2BlendingDevice which hides some of the
streaming details of the VSP2 and has some level of error recovery. Both
classes include a fair bit of logging and error reporting.

The patch is written with Wayland compositors in mind, but should work for
other use cases as well.

This is just the basic support to make compositing work, additional features
may be added in subsequent patches, i.e:

- Auto-detect VSP2 (-feature-vsp2 currently needs to be explicitly enabled).
- Support for setting the alpha value of a layer.
- Support clipping layers.
- Support for scaling layers.
- Support for other output formats than RGBA32.
- Hardware cursor support.
- Support foreign layers below the main Qt layer.
- Support for memory mapped and user pointer buffer types (currently only DMA
  buffers are supported).

Change-Id: I1917d2dbdbaeded0d9c021baaa799d56afe1a9bd
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 113 insertions, 0 deletions

diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_vsp2/qlinuxmediadevice.h b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_vsp2/qlinuxmediadevice.h
new file mode 100644
index 0000000000..848099eb46
--- /dev/null
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_vsp2/qlinuxmediadevice.h
@@ -0,0 +1,113 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QLINUXMEDIADEVICE_H
+#define QLINUXMEDIADEVICE_H
+
+#include <linux/v4l2-mediabus.h>
+
+#include <QtCore/qglobal.h>
+#include <QtCore/QString>
+
+QT_BEGIN_NAMESPACE
+
+class QSize;
+class QRect;
+
+class QLinuxMediaDevice
+{
+public:
+    QLinuxMediaDevice(const QString &devicePath);
+    ~QLinuxMediaDevice();
+
+    QString model();
+    QString deviceName();
+    bool resetLinks();
+    struct media_link *parseLink(const QString &link);
+    struct media_pad *parsePad(const QString &pad);
+    bool enableLink(struct media_link *link);
+    bool disableLink(struct media_link *link);
+    struct media_entity *getEntity(const QString &name);
+    int openVideoDevice(const QString &name);
+
+    class CaptureSubDevice
+    {
+    public:
+        CaptureSubDevice(QLinuxMediaDevice *mediaDevice, const QString &name);
+        bool setFormat(const QSize &size, uint32_t pixelFormat = V4L2_PIX_FMT_ABGR32); //TODO: fix to match output device
+        bool clearBuffers();
+        bool requestBuffer();
+        bool queueBuffer(int dmabufFd, const QSize &bufferSize);
+        bool dequeueBuffer();
+        bool streamOn();
+        bool streamOff();
+    private:
+        int m_subdevFd = -1;
+    };
+
+    class OutputSubDevice
+    {
+    public:
+        OutputSubDevice(QLinuxMediaDevice *mediaDevice, const QString &name);
+        bool setFormat(const QSize &size, uint32_t pixelFormat, uint32_t bytesPerLine);
+        bool clearBuffers();
+        bool requestBuffer();
+        bool queueBuffer(int dmabufFd, uint bytesUsed, uint length);
+        bool streamOn();
+        bool streamOff();
+    private:
+        int m_subdevFd = -1;
+    };
+
+    static bool setSubdevFormat(struct media_pad *pad, const QSize &size, uint32_t mbusFormat = MEDIA_BUS_FMT_ARGB8888_1X32);
+
+    static bool setSubdevSelection(struct media_pad *pad, const QRect &geometry, uint target);
+    static bool setSubdevCrop(struct media_pad *pad, const QRect &geometry);
+    static bool setSubdevCompose(struct media_pad *pad, const QRect &geometry);
+
+private:
+    static bool streamOn(int subDeviceFd, v4l2_buf_type bufferType);
+    static bool streamOff(int subDeviceFd, v4l2_buf_type bufferType);
+    struct media_device *m_mediaDevice = nullptr;
+    const struct media_device_info *m_info = nullptr;
+};
+
+QT_END_NAMESPACE
+
+#endif // QLINUXMEDIADEVICE_H