From 788ae5891ab4fc797775eaff827e88e566d2b1ec Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Fri, 6 May 2022 18:30:19 +0200
Subject: [PATCH] backends/drm: zero metadata for unused planes

The kernel may fail requests if data for unused planes is non-zero.
---
 src/backends/drm/drm_buffer_gbm.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/backends/drm/drm_buffer_gbm.cpp b/src/backends/drm/drm_buffer_gbm.cpp
index 138496b681..a4bd5d3fbb 100644
--- a/src/backends/drm/drm_buffer_gbm.cpp
+++ b/src/backends/drm/drm_buffer_gbm.cpp
@@ -32,27 +32,39 @@ namespace KWin
 static std::array<uint32_t, 4> getHandles(gbm_bo *bo)
 {
     std::array<uint32_t, 4> ret;
-    for (int i = 0; i < gbm_bo_get_plane_count(bo); i++) {
+    int i = 0;
+    for (; i < gbm_bo_get_plane_count(bo); i++) {
         ret[i] = gbm_bo_get_handle(bo).u32;
     }
+    for (; i < 4; i++) {
+        ret[i] = 0;
+    }
     return ret;
 }
 
 static std::array<uint32_t, 4> getStrides(gbm_bo *bo)
 {
     std::array<uint32_t, 4> ret;
-    for (int i = 0; i < gbm_bo_get_plane_count(bo); i++) {
+    int i = 0;
+    for (; i < gbm_bo_get_plane_count(bo); i++) {
         ret[i] = gbm_bo_get_stride_for_plane(bo, i);
     }
+    for (; i < 4; i++) {
+        ret[i] = 0;
+    }
     return ret;
 }
 
 static std::array<uint32_t, 4> getOffsets(gbm_bo *bo)
 {
     std::array<uint32_t, 4> ret;
-    for (int i = 0; i < gbm_bo_get_plane_count(bo); i++) {
+    int i = 0;
+    for (; i < gbm_bo_get_plane_count(bo); i++) {
         ret[i] = gbm_bo_get_offset(bo, i);
     }
+    for (; i < 4; i++) {
+        ret[i] = 0;
+    }
     return ret;
 }