If a driver supports this capability, it means that there would be an additional signalling mechanism for a page flip completion in addition to out_fence or DRM_MODE_PAGE_FLIP_EVENT.
This capability may only be relevant for Virtual KMS drivers and is currently used only by virtio-gpu. Also, it can provide a potential solution for: https://gitlab.freedesktop.org/wayland/weston/-/issues/514
Signed-off-by: Vivek Kasireddy vivek.kasireddy@intel.com --- drivers/gpu/drm/drm_ioctl.c | 3 +++ include/drm/drm_mode_config.h | 8 ++++++++ include/uapi/drm/drm.h | 1 + 3 files changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 8b8744dcf691..8a420844f8bc 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -302,6 +302,9 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_ case DRM_CAP_CRTC_IN_VBLANK_EVENT: req->value = 1; break; + case DRM_CAP_RELEASE_FENCE: + req->value = dev->mode_config.release_fence; + break; default: return -EINVAL; } diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index 12b964540069..944bebf359d7 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -935,6 +935,14 @@ struct drm_mode_config { */ bool normalize_zpos;
+ /** + * @release_fence: + * + * If this option is set, it means there would be an additional signalling + * mechanism for a page flip completion. + */ + bool release_fence; + /** * @modifiers_property: Plane property to list support modifier/format * combination. diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 3b810b53ba8b..8b8985f65581 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -767,6 +767,7 @@ struct drm_gem_open { * Documentation/gpu/drm-mm.rst, section "DRM Sync Objects". */ #define DRM_CAP_SYNCOBJ_TIMELINE 0x14 +#define DRM_CAP_RELEASE_FENCE 0x15
/* DRM_IOCTL_GET_CAP ioctl argument type */ struct drm_get_cap {