[platforms/drm] Add support for rotation property on the Plane

Summary:
A preparation step to support rotation of outputs. The idea is to rotate
using DRM directly and not add it to the compositors. With this change
and a small hack to try it, I was able to rotate the screen.

Reviewers: #kwin, #plasma, subdiff

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D8582

plugins/platforms/drm/drm_object_plane.cpp

@@ -75,6 +75,7 @@ bool DrmPlane::initProps()
         QByteArrayLiteral("CRTC_H"),
         QByteArrayLiteral("FB_ID"),
         QByteArrayLiteral("CRTC_ID"),
+        QByteArrayLiteral("rotation")
     };
 
     QVector<QByteArray> typeNames = {
@@ -119,6 +120,11 @@ void DrmPlane::setNext(DrmBuffer *b){
     m_next = b;
 }
 
+void DrmPlane::setTransformation(Transformations t)
+{
+    setValue(int(PropertyIndex::Rotation), int(t));
+}
+
 bool DrmPlane::atomicPopulate(drmModeAtomicReq *req)
 {
     bool ret = true;

plugins/platforms/drm/drm_object_plane.h

@@ -48,6 +48,7 @@ public:
         CrtcH,
         FbId,
         CrtcId,
+        Rotation,
         Count
     };
 
@@ -57,7 +58,17 @@ public:
         Overlay,
         Count
     };
-    
+
+    enum class Transformation {
+        Rotate0 = 1 << 0,
+        Rotate90 = 1 << 1,
+        Rotate180 = 1 << 2,
+        Rotate270 = 1 << 3,
+        ReflectX = 1 << 4,
+        ReflectY = 1 << 5
+    };
+    Q_DECLARE_FLAGS(Transformations, Transformation);
+
     bool atomicInit();
     bool initProps();
     TypeIndex type();
@@ -79,6 +90,7 @@ public:
         m_current = b;
     }
     void setNext(DrmBuffer *b);
+    void setTransformation(Transformations t);
 
     bool atomicPopulate(drmModeAtomicReq *req);
     void flipBuffer();
@@ -97,5 +109,7 @@ private:
 
 }
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(KWin::DrmPlane::Transformations)
+
 #endif