backends/drm: Pass DrmGpu to page flip handler through user data

The page flip handler can be simpler if it gets the gpu through user
data. It also removes a usage of the Application singleton.

src/backends/drm/drm_backend.cpp

@@ -670,14 +670,6 @@ DrmGpu *DrmBackend::findGpu(dev_t deviceId) const
     return it == m_gpus.end() ? nullptr : it->get();
 }
 
-DrmGpu *DrmBackend::findGpuByFd(int fd) const
-{
-    auto it = std::find_if(m_gpus.begin(), m_gpus.end(), [fd](const auto &gpu) {
-        return gpu->fd() == fd;
-    });
-    return it == m_gpus.end() ? nullptr : it->get();
-}
-
 bool DrmBackend::applyOutputChanges(const OutputConfiguration &config)
 {
     QVector<DrmOutput *> toBeEnabled;

src/backends/drm/drm_backend.h

@@ -68,7 +68,6 @@ public:
 
     DrmGpu *primaryGpu() const;
     DrmGpu *findGpu(dev_t deviceId) const;
-    DrmGpu *findGpuByFd(int fd) const;
 
     bool isActive() const;
 

src/backends/drm/drm_gpu.cpp

@@ -22,7 +22,6 @@
 #include "egl_gbm_backend.h"
 #include "gbm_dmabuf.h"
 #include "logging.h"
-#include "main.h"
 #include "renderloop_p.h"
 #include "session.h"
 #include "wayland/drmleasedevice_v1_interface.h"
@@ -527,16 +526,10 @@ static std::chrono::nanoseconds convertTimestamp(clockid_t sourceClock, clockid_
 
 void DrmGpu::pageFlipHandler(int fd, unsigned int sequence, unsigned int sec, unsigned int usec, unsigned int crtc_id, void *user_data)
 {
+    Q_UNUSED(fd)
     Q_UNUSED(sequence)
-    Q_UNUSED(user_data)
+
-    auto backend = dynamic_cast<DrmBackend *>(kwinApp()->platform());
+    DrmGpu *gpu = static_cast<DrmGpu *>(user_data);
-    if (!backend) {
-        return;
-    }
-    auto gpu = backend->findGpuByFd(fd);
-    if (!gpu) {
-        return;
-    }
 
     // The static_cast<> here are for a 32-bit environment where
     // sizeof(time_t) == sizeof(unsigned int) == 4 . Putting @p sec

src/backends/drm/drm_pipeline.cpp

@@ -145,12 +145,13 @@ DrmPipeline::Error DrmPipeline::commitPipelinesAtomic(const QVector<DrmPipeline
     } else {
         flags |= DRM_MODE_ATOMIC_NONBLOCK;
     }
-    if (drmModeAtomicCommit(pipelines[0]->gpu()->fd(), req, (flags & (~DRM_MODE_PAGE_FLIP_EVENT)) | DRM_MODE_ATOMIC_TEST_ONLY, nullptr) != 0) {
+    DrmGpu *gpu = pipelines[0]->gpu();
+    if (drmModeAtomicCommit(gpu->fd(), req, (flags & (~DRM_MODE_PAGE_FLIP_EVENT)) | DRM_MODE_ATOMIC_TEST_ONLY, nullptr) != 0) {
         qCDebug(KWIN_DRM) << "Atomic test for" << mode << "failed!" << strerror(errno);
         failed();
         return errnoToError();
     }
-    if (mode != CommitMode::Test && drmModeAtomicCommit(pipelines[0]->gpu()->fd(), req, flags, nullptr) != 0) {
+    if (mode != CommitMode::Test && drmModeAtomicCommit(gpu->fd(), req, flags, gpu) != 0) {
         qCCritical(KWIN_DRM) << "Atomic commit failed! This should never happen!" << strerror(errno);
         failed();
         return errnoToError();

src/backends/drm/drm_pipeline_legacy.cpp

@@ -30,7 +30,7 @@ DrmPipeline::Error DrmPipeline::presentLegacy()
         }
     }
     const auto buffer = m_pending.layer->currentBuffer();
-    if (drmModePageFlip(gpu()->fd(), m_pending.crtc->id(), buffer->framebufferId(), DRM_MODE_PAGE_FLIP_EVENT, nullptr) != 0) {
+    if (drmModePageFlip(gpu()->fd(), m_pending.crtc->id(), buffer->framebufferId(), DRM_MODE_PAGE_FLIP_EVENT, gpu()) != 0) {
         qCWarning(KWIN_DRM) << "Page flip failed:" << strerror(errno);
         return errnoToError();
     }