From 757ed91a5dd20aaa835fb995f46f9ae94ce007eb Mon Sep 17 00:00:00 2001
From: Rohan Garg <rohan@garg.io>
Date: Sun, 22 Apr 2018 15:17:53 +0200
Subject: [PATCH] Handle errors with drmModeSetCursor instead of silently
 failing

Summary:
Make sure we switch to a software cursor when drmModeSetCursor
fails.

Reviewers: #kwin, graesslin

Subscribers: davidedmundson, bshah, graesslin, kwin, #kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D12447
---
 plugins/platforms/drm/drm_backend.cpp |  8 ++++++--
 plugins/platforms/drm/drm_output.cpp  | 18 ++++++++++++------
 plugins/platforms/drm/drm_output.h    |  6 +++---
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/plugins/platforms/drm/drm_backend.cpp b/plugins/platforms/drm/drm_backend.cpp
index 90ed4579e2..2bcc7c96b2 100644
--- a/plugins/platforms/drm/drm_backend.cpp
+++ b/plugins/platforms/drm/drm_backend.cpp
@@ -624,7 +624,9 @@ void DrmBackend::initCursor()
             }
             for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
                 if (m_cursorEnabled) {
-                    (*it)->showCursor();
+                    if (!(*it)->showCursor()) {
+                        setSoftWareCursor(true);
+                    }
                 } else {
                     (*it)->hideCursor();
                 }
@@ -653,7 +655,9 @@ void DrmBackend::setCursor()
 {
     if (m_cursorEnabled) {
         for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
-            (*it)->showCursor();
+            if (!(*it)->showCursor()) {
+                setSoftWareCursor(true);
+            }
         }
     }
     markCursorAsRendered();
diff --git a/plugins/platforms/drm/drm_output.cpp b/plugins/platforms/drm/drm_output.cpp
index bd3dac1a8c..fb09ae1d27 100644
--- a/plugins/platforms/drm/drm_output.cpp
+++ b/plugins/platforms/drm/drm_output.cpp
@@ -96,24 +96,30 @@ void DrmOutput::releaseGbm()
     }
 }
 
-void DrmOutput::hideCursor()
+bool DrmOutput::hideCursor()
 {
-    drmModeSetCursor(m_backend->fd(), m_crtc->id(), 0, 0, 0);
+    return drmModeSetCursor(m_backend->fd(), m_crtc->id(), 0, 0, 0) == 0;
 }
 
-void DrmOutput::showCursor(DrmDumbBuffer *c)
+bool DrmOutput::showCursor(DrmDumbBuffer *c)
 {
     const QSize &s = c->size();
-    drmModeSetCursor(m_backend->fd(), m_crtc->id(), c->handle(), s.width(), s.height());
+    return drmModeSetCursor(m_backend->fd(), m_crtc->id(), c->handle(), s.width(), s.height()) == 0;
 }
 
-void DrmOutput::showCursor()
+bool DrmOutput::showCursor()
 {
-    showCursor(m_cursor[m_cursorIndex]);
+    const bool ret = showCursor(m_cursor[m_cursorIndex]);
+    if (!ret) {
+        return ret;
+    }
+
     if (m_hasNewCursor) {
         m_cursorIndex = (m_cursorIndex + 1) % 2;
         m_hasNewCursor = false;
     }
+
+    return ret;
 }
 
 void DrmOutput::updateCursor()
diff --git a/plugins/platforms/drm/drm_output.h b/plugins/platforms/drm/drm_output.h
index 9e87b2e30a..2206bfac22 100644
--- a/plugins/platforms/drm/drm_output.h
+++ b/plugins/platforms/drm/drm_output.h
@@ -66,9 +66,9 @@ public:
     };
     virtual ~DrmOutput();
     void releaseGbm();
-    void showCursor(DrmDumbBuffer *buffer);
-    void showCursor();
-    void hideCursor();
+    bool showCursor(DrmDumbBuffer *buffer);
+    bool showCursor();
+    bool hideCursor();
     void updateCursor();
     void moveCursor(const QPoint &globalPos);
     bool init(drmModeConnector *connector);