File 0001-gbm-Add-fallback-for-drmPrimeHandleToFD.patch of Package qt6-webengine

From ea67e8c8466e298a969df4c02a66798d408faaaa Mon Sep 17 00:00:00 2001
From: Peter Varga <pvarga@inf.u-szeged.hu>
Date: Wed, 23 Apr 2025 09:45:33 +0200
Subject: [PATCH] Add fallback for drmPrimeHandleToFD()

drmPrimeHandleToFD() does not seem to work with legacy radeon driver and
returns invalid fd and it may cause QtWebEngine crash.

Chromium replaced gbm_bo_get_plane_fd() with drmPrimeHandleToFD() to
provide file descriptors per plane basis, see https://crrev.com/c/1273059

Since then, Mesa introduced new GBM API to provide fds per plane basis,
see https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5442

To keep legacy GPU drivers supported, use the new GBM API as a fallback
if the drmPrimeHandleToFD() fails.

Fixes: QTBUG-135935
Change-Id: I79f54f861916d3b19f743cab183f756657094b09
Done-with: Kevin B. Hendricks
Reviewed-on: https://codereview.qt-project.org/c/qt/qtwebengine-chromium/+/641190
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
---
 src/3rdparty/chromium/ui/gfx/linux/gbm_wrapper.cc | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/3rdparty/chromium/ui/gfx/linux/gbm_wrapper.cc b/src/3rdparty/chromium/ui/gfx/linux/gbm_wrapper.cc
index 39d9fe6..7b75b74 100644
--- a/src/3rdparty/chromium/ui/gfx/linux/gbm_wrapper.cc
+++ b/src/3rdparty/chromium/ui/gfx/linux/gbm_wrapper.cc
@@ -76,14 +76,26 @@ base::ScopedFD GetPlaneFdForBo(gbm_bo* bo, size_t plane) {
   int ret;
   // Use DRM_RDWR to allow the fd to be mappable in another process.
   ret = drmPrimeHandleToFD(dev_fd, plane_handle, DRM_CLOEXEC | DRM_RDWR, &fd);
-  PLOG_IF(ERROR, ret != 0) << "Failed to get fd for plane.";
+  PLOG_IF(WARNING, ret != 0) << "Failed to get fd for plane with libdrm.";
 
   // Older DRM implementations blocked DRM_RDWR, but gave a read/write mapping
   // anyways
   if (ret) {
     ret = drmPrimeHandleToFD(dev_fd, plane_handle, DRM_CLOEXEC, &fd);
+    PLOG_IF(WARNING, ret != 0) << "Failed to get fd for plane even without DRM_RDWR.";
   }
 
+#if BUILDFLAG(IS_QTWEBENGINE)
+  // drmPrimeHandleToFD() does not work with legacy radeon driver. Fallback to
+  // gbm_bo_get_fd_for_plane() which does provide fds per plane basis.
+  if (ret) {
+    fd = gbm_bo_get_fd_for_plane(bo, plane);
+    ret = (fd == -1) ? -1 : 0;
+    PLOG_IF(WARNING, ret != 0) << "Failed to get fd for plane even with GBM.";
+  }
+#endif
+
+  LOG_IF(ERROR, ret != 0) << "Failed to get fd for plane.";
   return ret ? base::ScopedFD() : base::ScopedFD(fd);
 #endif
 }
-- 
2.49.0