[mutter] drm-buffer: Clarify misleading error message on drmModeAddFB2 failure

[Marge Bot <marge-bot src gnome org>]

commit 100c02e5146be08647e2e5a09fda85c42e3a234b
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Thu Oct 13 16:06:57 2022 +0800

    drm-buffer: Clarify misleading error message on drmModeAddFB2 failure
    
    The real error is more likely to do with the drmModeAddFB2 failure than
    the format not being compatible with drmModeAddFB.
    
    Related: https://gitlab.gnome.org/GNOME/mutter/-/issues/2379
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2656>

 src/backends/native/meta-drm-buffer.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/src/backends/native/meta-drm-buffer.c b/src/backends/native/meta-drm-buffer.c
index 86dfb16da6..c7eeca4f60 100644
--- a/src/backends/native/meta-drm-buffer.c
+++ b/src/backends/native/meta-drm-buffer.c
@@ -127,10 +127,12 @@ meta_drm_buffer_do_ensure_fb_id (MetaDrmBuffer        *buffer,
         {
           g_set_error (error,
                        G_IO_ERROR,
-                       G_IO_ERROR_FAILED,
-                       "drmModeAddFB does not support format '%s' (0x%x)",
-                       meta_drm_format_to_string (&tmp, fb_args->format),
-                       fb_args->format);
+                       g_io_error_from_errno (errno),
+                       "drmModeAddFB2 failed (%s) and drmModeAddFB cannot be "
+                       "used as a fallback because format=0x%x (%s).",
+                       g_strerror (errno),
+                       fb_args->format,
+                       meta_drm_format_to_string (&tmp, fb_args->format));
           return FALSE;
         }