diff --git a/src/backends/drm/drm_buffer.cpp b/src/backends/drm/drm_buffer.cpp
index 55aeff877f..4220ceca52 100644
--- a/src/backends/drm/drm_buffer.cpp
+++ b/src/backends/drm/drm_buffer.cpp
@@ -23,13 +23,38 @@
 namespace KWin
 {
 
-DrmBuffer:: DrmBuffer(DrmGpu *gpu, uint32_t format, uint64_t modifier)
+DrmBuffer::DrmBuffer(DrmGpu *gpu, uint32_t format, uint64_t modifier)
     : m_gpu(gpu)
     , m_format(format)
     , m_modifier(modifier)
 {
 }
 
+quint32 DrmBuffer::bufferId() const
+{
+    return m_bufferId;
+}
+
+const QSize &DrmBuffer::size() const
+{
+    return m_size;
+}
+
+DrmGpu *DrmBuffer::gpu() const
+{
+    return m_gpu;
+}
+
+uint32_t DrmBuffer::format() const
+{
+    return m_format;
+}
+
+uint64_t DrmBuffer::modifier() const
+{
+    return m_modifier;
+}
+
 // DrmDumbBuffer
 DrmDumbBuffer::DrmDumbBuffer(DrmGpu *gpu, const QSize &size, uint32_t drmFormat)
     : DrmBuffer(gpu, drmFormat, DRM_FORMAT_MOD_LINEAR)
@@ -105,4 +130,24 @@ bool DrmDumbBuffer::map(QImage::Format format)
     return !m_image->isNull();
 }
 
+quint32 DrmDumbBuffer::handle() const
+{
+    return m_handle;
+}
+
+QImage *DrmDumbBuffer::image() const
+{
+    return m_image;
+}
+
+void *DrmDumbBuffer::data() const
+{
+    return m_memory;
+}
+
+quint32 DrmDumbBuffer::stride() const
+{
+    return m_stride;
+}
+
 }
diff --git a/src/backends/drm/drm_buffer.h b/src/backends/drm/drm_buffer.h
index ea22babcf8..02bc8b13c3 100644
--- a/src/backends/drm/drm_buffer.h
+++ b/src/backends/drm/drm_buffer.h
@@ -25,23 +25,11 @@ public:
 
     virtual bool needsModeChange(DrmBuffer *b) const {Q_UNUSED(b) return false;}
 
-    quint32 bufferId() const {
-        return m_bufferId;
-    }
-
-    const QSize &size() const {
-        return m_size;
-    }
-
-    DrmGpu *gpu() const {
-        return m_gpu;
-    }
-    uint32_t format() const {
-        return m_format;
-    }
-    uint64_t modifier() const {
-        return m_modifier;
-    }
+    quint32 bufferId() const;
+    const QSize &size() const;
+    DrmGpu *gpu() const;
+    uint32_t format() const;
+    uint64_t modifier() const;
 
 protected:
     quint32 m_bufferId = 0;
@@ -60,18 +48,10 @@ public:
     bool needsModeChange(DrmBuffer *b) const override;
 
     bool map(QImage::Format format = QImage::Format_RGB32);
-    quint32 handle() const {
-        return m_handle;
-    }
-    QImage *image() const {
-        return m_image;
-    }
-    void *data() const {
-        return m_memory;
-    }
-    quint32 stride() const {
-        return m_stride;
-    }
+    quint32 handle() const;
+    QImage *image() const;
+    void *data() const;
+    quint32 stride() const;
 
 private:
     quint32 m_handle = 0;
diff --git a/src/backends/drm/drm_buffer_gbm.cpp b/src/backends/drm/drm_buffer_gbm.cpp
index 15c832b902..280a5414f4 100644
--- a/src/backends/drm/drm_buffer_gbm.cpp
+++ b/src/backends/drm/drm_buffer_gbm.cpp
@@ -88,6 +88,21 @@ KWaylandServer::ClientBuffer *GbmBuffer::clientBuffer() const
     return m_clientBuffer;
 }
 
+gbm_bo* GbmBuffer::getBo() const
+{
+    return m_bo;
+}
+
+void *GbmBuffer::mappedData() const
+{
+    return m_data;
+}
+
+uint32_t GbmBuffer::stride() const
+{
+    return m_stride;
+}
+
 
 DrmGbmBuffer::DrmGbmBuffer(DrmGpu *gpu, GbmSurface *surface, gbm_bo *bo)
     : DrmBuffer(gpu, gbm_bo_get_format(bo), gbm_bo_get_modifier(bo)), GbmBuffer(surface, bo)
@@ -151,4 +166,18 @@ void DrmGbmBuffer::initialize()
     gbm_bo_set_user_data(m_bo, this, nullptr);
 }
 
+bool DrmGbmBuffer::needsModeChange(DrmBuffer *b) const
+{
+    if (DrmGbmBuffer *sb = dynamic_cast<DrmGbmBuffer*>(b)) {
+        return hasBo() != sb->hasBo();
+    } else {
+        return true;
+    }
+}
+
+bool DrmGbmBuffer::hasBo() const
+{
+    return m_bo != nullptr;
+}
+
 }
diff --git a/src/backends/drm/drm_buffer_gbm.h b/src/backends/drm/drm_buffer_gbm.h
index 1e3ae8a022..ee7c0149e1 100644
--- a/src/backends/drm/drm_buffer_gbm.h
+++ b/src/backends/drm/drm_buffer_gbm.h
@@ -34,20 +34,13 @@ public:
     GbmBuffer(gbm_bo *buffer, KWaylandServer::ClientBuffer *clientBuffer);
     virtual ~GbmBuffer();
 
-    gbm_bo* getBo() const {
-        return m_bo;
-    }
-
     void releaseBuffer();
-
     bool map(uint32_t flags);
-    void *mappedData() const {
-        return m_data;
-    }
-    uint32_t stride() const {
-        return m_stride;
-    }
+
+    void *mappedData() const;
+    uint32_t stride() const;
     KWaylandServer::ClientBuffer *clientBuffer() const;
+    gbm_bo* getBo() const;
 
 protected:
     GbmSurface *m_surface = nullptr;
@@ -66,17 +59,8 @@ public:
     DrmGbmBuffer(DrmGpu *gpu, gbm_bo *buffer, KWaylandServer::ClientBuffer *clientBuffer);
     ~DrmGbmBuffer() override;
 
-    bool needsModeChange(DrmBuffer *b) const override {
-        if (DrmGbmBuffer *sb = dynamic_cast<DrmGbmBuffer*>(b)) {
-            return hasBo() != sb->hasBo();
-        } else {
-            return true;
-        }
-    }
-
-    bool hasBo() const {
-        return m_bo != nullptr;
-    }
+    bool needsModeChange(DrmBuffer *b) const override;
+    bool hasBo() const;
 
 private:
     void initialize();
diff --git a/src/backends/drm/drm_lease_output.cpp b/src/backends/drm/drm_lease_output.cpp
index 766c3add23..a2858824bf 100644
--- a/src/backends/drm/drm_lease_output.cpp
+++ b/src/backends/drm/drm_lease_output.cpp
@@ -65,4 +65,14 @@ void DrmLeaseOutput::leaseEnded()
     m_lease = nullptr;
 }
 
+KWaylandServer::DrmLeaseV1Interface *DrmLeaseOutput::lease() const
+{
+    return m_lease;
+}
+
+DrmPipeline *DrmLeaseOutput::pipeline() const
+{
+    return m_pipeline;
+}
+
 }
diff --git a/src/backends/drm/drm_lease_output.h b/src/backends/drm/drm_lease_output.h
index 1b992b6fb9..ae8db03128 100644
--- a/src/backends/drm/drm_lease_output.h
+++ b/src/backends/drm/drm_lease_output.h
@@ -35,13 +35,8 @@ public:
     void leased(KWaylandServer::DrmLeaseV1Interface *lease);
     void leaseEnded();
 
-    KWaylandServer::DrmLeaseV1Interface *lease() const {
-        return m_lease;
-    }
-
-    DrmPipeline *pipeline() const {
-        return m_pipeline;
-    }
+    KWaylandServer::DrmLeaseV1Interface *lease() const;
+    DrmPipeline *pipeline() const;
 
 private:
     DrmPipeline *m_pipeline;
diff --git a/src/backends/drm/drm_virtual_output.cpp b/src/backends/drm/drm_virtual_output.cpp
index dd98723266..0deccfd264 100644
--- a/src/backends/drm/drm_virtual_output.cpp
+++ b/src/backends/drm/drm_virtual_output.cpp
@@ -93,4 +93,20 @@ QVector<uint64_t> DrmVirtualOutput::supportedModifiers(uint32_t drmFormat) const
     return {};
 }
 
+int DrmVirtualOutput::gammaRampSize() const
+{
+    return 200;
+}
+
+bool DrmVirtualOutput::setGammaRamp(const GammaRamp &gamma)
+{
+    Q_UNUSED(gamma);
+    return true;
+}
+
+bool DrmVirtualOutput::needsSoftwareTransformation() const
+{
+    return false;
+}
+
 }
diff --git a/src/backends/drm/drm_virtual_output.h b/src/backends/drm/drm_virtual_output.h
index 160999bb6d..8fb665adba 100644
--- a/src/backends/drm/drm_virtual_output.h
+++ b/src/backends/drm/drm_virtual_output.h
@@ -34,16 +34,9 @@ public:
     bool isFormatSupported(uint32_t drmFormat) const override;
     QVector<uint64_t> supportedModifiers(uint32_t drmFormat) const override;
 
-    int gammaRampSize() const override {
-        return 200;
-    }
-    bool setGammaRamp(const GammaRamp &gamma) override {
-        Q_UNUSED(gamma);
-        return true;
-    }
-    bool needsSoftwareTransformation() const override {
-        return false;
-    }
+    int gammaRampSize() const override;
+    bool setGammaRamp(const GammaRamp &gamma) override;
+    bool needsSoftwareTransformation() const override;
 
 private:
     void vblank(std::chrono::nanoseconds timestamp);
diff --git a/src/backends/drm/dumb_swapchain.cpp b/src/backends/drm/dumb_swapchain.cpp
index 4b20e332c6..5af8bd4187 100644
--- a/src/backends/drm/dumb_swapchain.cpp
+++ b/src/backends/drm/dumb_swapchain.cpp
@@ -71,4 +71,19 @@ uint32_t DumbSwapchain::drmFormat() const
     return m_format;
 }
 
+qsizetype DumbSwapchain::slotCount() const
+{
+    return m_slots.count();
+}
+
+QSize DumbSwapchain::size() const
+{
+    return m_size;
+}
+
+bool DumbSwapchain::isEmpty() const
+{
+    return m_slots.isEmpty();
+}
+
 }
diff --git a/src/backends/drm/dumb_swapchain.h b/src/backends/drm/dumb_swapchain.h
index 917a27a2c7..faa6672aed 100644
--- a/src/backends/drm/dumb_swapchain.h
+++ b/src/backends/drm/dumb_swapchain.h
@@ -29,17 +29,9 @@ public:
     QSharedPointer<DrmDumbBuffer> currentBuffer() const;
     void releaseBuffer(QSharedPointer<DrmDumbBuffer> buffer);
 
-    qsizetype slotCount() const {
-        return m_slots.count();
-    }
-
-    QSize size() const {
-        return m_size;
-    }
-
-    bool isEmpty() const {
-        return m_slots.isEmpty();
-    }
+    qsizetype slotCount() const;
+    QSize size() const;
+    bool isEmpty() const;
     uint32_t drmFormat() const;
 
 private:
diff --git a/src/backends/drm/gbm_dmabuf.cpp b/src/backends/drm/gbm_dmabuf.cpp
index 2bc53a6a00..3a23d647b6 100644
--- a/src/backends/drm/gbm_dmabuf.cpp
+++ b/src/backends/drm/gbm_dmabuf.cpp
@@ -28,8 +28,17 @@ GbmDmaBuf::~GbmDmaBuf()
     gbm_bo_destroy(m_bo);
 }
 
+int GbmDmaBuf::fd() const
+{
+    return m_fd;
+}
 
-KWin::GbmDmaBuf *GbmDmaBuf::createBuffer(const QSize &size, gbm_device *device)
+quint32 GbmDmaBuf::stride() const
+{
+    return gbm_bo_get_stride(m_bo);
+}
+
+GbmDmaBuf *GbmDmaBuf::createBuffer(const QSize &size, gbm_device *device)
 {
     if (!device) {
         return nullptr;
diff --git a/src/backends/drm/gbm_dmabuf.h b/src/backends/drm/gbm_dmabuf.h
index bd3c203561..57ebf2ac26 100644
--- a/src/backends/drm/gbm_dmabuf.h
+++ b/src/backends/drm/gbm_dmabuf.h
@@ -19,13 +19,8 @@ class GbmDmaBuf : public DmaBufTexture
 public:
     ~GbmDmaBuf();
 
-    int fd() const override
-    {
-        return m_fd;
-    }
-    quint32 stride() const override {
-        return gbm_bo_get_stride(m_bo);
-    }
+    int fd() const override;
+    quint32 stride() const override;
 
     static GbmDmaBuf *createBuffer(const QSize &size, gbm_device *device);
 
diff --git a/src/backends/drm/gbm_surface.cpp b/src/backends/drm/gbm_surface.cpp
index d998f74301..94278ea493 100644
--- a/src/backends/drm/gbm_surface.cpp
+++ b/src/backends/drm/gbm_surface.cpp
@@ -116,4 +116,19 @@ QSharedPointer<DrmGbmBuffer> GbmSurface::currentDrmBuffer() const
     return m_currentDrmBuffer;
 }
 
+EGLSurface GbmSurface::eglSurface() const
+{
+    return m_eglSurface;
+}
+
+QSize GbmSurface::size() const
+{
+    return m_size;
+}
+
+bool GbmSurface::isValid() const
+{
+    return m_surface != nullptr && m_eglSurface != EGL_NO_SURFACE;
+}
+
 }
diff --git a/src/backends/drm/gbm_surface.h b/src/backends/drm/gbm_surface.h
index e76a722e13..f7bca28394 100644
--- a/src/backends/drm/gbm_surface.h
+++ b/src/backends/drm/gbm_surface.h
@@ -36,17 +36,9 @@ public:
     QSharedPointer<GbmBuffer> currentBuffer() const;
     QSharedPointer<DrmGbmBuffer> currentDrmBuffer() const;
 
-    EGLSurface eglSurface() const {
-        return m_eglSurface;
-    }
-
-    QSize size() const {
-        return m_size;
-    }
-
-    bool isValid() const {
-        return m_surface != nullptr && m_eglSurface != EGL_NO_SURFACE;
-    }
+    EGLSurface eglSurface() const;
+    QSize size() const;
+    bool isValid() const;
 
 private:
     gbm_surface *m_surface;