From 4f0273e5e66b0dd5917c4273d7f0ecaef1ecd146 Mon Sep 17 00:00:00 2001
From: Levi Neely <lkn@darkstar.example.net>
Date: Tue, 31 Mar 2026 13:50:05 +0200
Subject: [PATCH] =?UTF-8?q?wayland:=20fix=20SHM=20buffer=20format=20?=
 =?UTF-8?q?=E2=80=94=20DRM=5FFORMAT=5FARGB8888=20not=20WL=5FSHM=5FFORMAT?=
 =?UTF-8?q?=5FARGB8888?=
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WL_SHM_FORMAT_ARGB8888 == 0, which the DRM/GLES2 renderer interprets as
DRM_FORMAT_INVALID.  This caused:
  - "Unsupported pixel format 0x0" on the first frame upload attempt
  - wlr_texture_from_buffer assertion failure when the scene renderer
    retried the upload lazily during an active render pass

Use DRM_FORMAT_ARGB8888 (0x34325241) from <libdrm/drm_fourcc.h> instead.
Texture creation now succeeds at wlr_scene_buffer_set_buffer time, so
the lazy path is never reached.

Verified: steel-blue test square visible in nested Sway session; smoke
test PASS.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 src/backend/wayland/wl_backend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/backend/wayland/wl_backend.c b/src/backend/wayland/wl_backend.c
index ac99a42..cab478e 100644
--- a/src/backend/wayland/wl_backend.c
+++ b/src/backend/wayland/wl_backend.c
@@ -130,6 +130,7 @@
 #include <wlr/types/wlr_scene.h>       /* Phase 18: scene graph compositing */
 #include <wlr/render/allocator.h>      /* Phase 18: buffer allocator */
 #include <wlr/types/wlr_buffer.h>      /* Phase 29+: WM-owned SHM surface buffers */
+#include <libdrm/drm_fourcc.h>        /* Phase 29+: DRM_FORMAT_ARGB8888 */
 #include <pixman.h>                    /* Phase 29+: software pixel rendering */
 #include <wlr/types/wlr_cursor.h>      /* Phase 23: hardware cursor tracking */
 #include <wlr/types/wlr_xcursor_manager.h> /* Phase 23: xcursor theme */
@@ -2421,7 +2422,7 @@ shm_buf_begin_data_ptr(struct wlr_buffer *buf, uint32_t flags,
     struct wm_shm_surface *s = wl_container_of(buf, s, wlr_buf);
     (void)flags;
     *out_data   = s->data;
-    *out_fmt    = WL_SHM_FORMAT_ARGB8888;
+    *out_fmt    = DRM_FORMAT_ARGB8888;
     *out_stride = s->stride;
     return true;
 }