[platforms/hwcomposer] Support for hwcomposer 1.4 and 1.5 version

Summary:
HWcomposer version 1.4 introduced setPowerMode, which replaces the
blank(). This adds support for it. There are various code paths
possible,

- If KWin is built against hwcomposer 1.3 headers, then setPowerMode
code is not compiled in, and it will use blank to turn display off.

- If KWin is built against hwcomposer 1.4 headers, it will have
setPowerMode code path compiled in. It will be used only on devices with
1.4 and 1.5 version of hwcomposer.

This is slightly insane, because Android can report hwcomposer 1.5 even
when headers are of 1.4 version..

Test Plan: Tested this on Nexus 5X which reports 1.5 version of hwcomposer

Reviewers: graesslin, #plasma

Reviewed By: graesslin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D3686

plugins/platforms/hwcomposer/hwcomposer_backend.cpp

@@ -223,6 +223,14 @@ void HwcomposerBackend::init()
     // unblank, setPowerMode?
     m_device = hwcDevice;
 
+	m_hwcVersion = m_device->common.version;
+	if ((m_hwcVersion & 0xffff0000) == 0) {
+		// Assume header version is always 1
+		uint32_t header_version = 1;
+		// Legacy version encoding
+		m_hwcVersion = (m_hwcVersion << 16) | header_version;
+	}
+
     // register callbacks
     hwc_procs_t *procs = new hwc_procs_t;
     procs->invalidate = [] (const struct hwc_procs* procs) {
@@ -309,8 +317,15 @@ void HwcomposerBackend::toggleBlankOutput()
     }
     m_outputBlank = !m_outputBlank;
     toggleScreenBrightness();
-    m_device->blank(m_device, 0, m_outputBlank ? 1 : 0);
-    // only disable Vsycn, enable happens after next frame rendered
+
+#if defined(HWC_DEVICE_API_VERSION_1_4) || defined(HWC_DEVICE_API_VERSION_1_5)
+    if (m_hwcVersion > HWC_DEVICE_API_VERSION_1_3)
+        m_device->setPowerMode(m_device, 0, m_outputBlank ? 0 : 2);
+    else
+#endif
+        m_device->blank(m_device, 0, m_outputBlank ? 1 : 0);
+
+    // only disable Vsync, enable happens after next frame rendered
     if (m_outputBlank) {
          enableVSync(false);
     }

plugins/platforms/hwcomposer/hwcomposer_backend.h

@@ -99,6 +99,7 @@ private:
     bool m_outputBlank = true;
     int m_refreshRate = 60000;
     int m_vsyncInterval = 16;
+    uint32_t m_hwcVersion;
     int m_oldScreenBrightness = 0x7f;
     bool m_hasVsync = false;
     QMutex m_vsyncMutex;