[mutter] kms/mode: Add API to create blob IDs for modes on demand

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

commit eb66449ab72f5dcb77e926c2abaa8f494a2c4f72
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Jun 4 17:20:36 2020 +0200

    kms/mode: Add API to create blob IDs for modes on demand
    
    Will be used by the atomic KMS backend.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1488>

 src/backends/native/meta-kms-mode-private.h |  3 +++
 src/backends/native/meta-kms-mode.c         | 34 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)
---
diff --git a/src/backends/native/meta-kms-mode-private.h b/src/backends/native/meta-kms-mode-private.h
index 3af6e2cd2b..5694db07a8 100644
--- a/src/backends/native/meta-kms-mode-private.h
+++ b/src/backends/native/meta-kms-mode-private.h
@@ -22,6 +22,9 @@
 
 #include "backends/native/meta-kms-mode.h"
 
+uint32_t meta_kms_mode_ensure_blob_id (MetaKmsMode  *mode,
+                                       GError      **error);
+
 void meta_kms_mode_free (MetaKmsMode *mode);
 
 MetaKmsMode * meta_kms_mode_new (MetaKmsImplDevice     *impl_device,
diff --git a/src/backends/native/meta-kms-mode.c b/src/backends/native/meta-kms-mode.c
index 68b5dc07f8..07c793f394 100644
--- a/src/backends/native/meta-kms-mode.c
+++ b/src/backends/native/meta-kms-mode.c
@@ -27,8 +27,33 @@ struct _MetaKmsMode
 {
   MetaKmsImplDevice *impl_device;
   drmModeModeInfo drm_mode;
+  uint32_t blob_id;
 };
 
+uint32_t
+meta_kms_mode_ensure_blob_id (MetaKmsMode  *mode,
+                              GError      **error)
+{
+  int fd;
+  int ret;
+
+  fd = meta_kms_impl_device_get_fd (mode->impl_device);
+
+  ret = drmModeCreatePropertyBlob (fd,
+                                   &mode->drm_mode,
+                                   sizeof (mode->drm_mode),
+                                   &mode->blob_id);
+  if (ret < 0)
+    {
+      g_set_error (error, G_IO_ERROR, g_io_error_from_errno (-ret),
+                   "drmModeCreatePropertyBlob: %s",
+                   g_strerror (-ret));
+      return 0;
+    }
+
+  return mode->blob_id;
+}
+
 const drmModeModeInfo *
 meta_kms_mode_get_drm_mode (MetaKmsMode *mode)
 {
@@ -38,6 +63,15 @@ meta_kms_mode_get_drm_mode (MetaKmsMode *mode)
 void
 meta_kms_mode_free (MetaKmsMode *mode)
 {
+  if (mode->blob_id)
+    {
+      int fd;
+
+      fd = meta_kms_impl_device_get_fd (mode->impl_device);
+
+      drmModeDestroyPropertyBlob (fd, mode->blob_id);
+    }
+
   g_free (mode);
 }