[PATCH 3/4] drm: introduce DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP

[Simon Ser]

This new kernel capability indicates whether async page-flips are
supported via the atomic uAPI. DRM clients can use it to check
for support before feeding DRM_MODE_PAGE_FLIP_ASYNC to the kernel.

Make it clear that DRM_CAP_ASYNC_PAGE_FLIP is for legacy uAPI only.

Signed-off-by: Simon Ser <contact at emersion.fr>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Joshua Ashton <joshua at froggi.es>
Cc: Melissa Wen <mwen at igalia.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Harry Wentland <hwentlan at amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
---
 drivers/gpu/drm/drm_ioctl.c |  5 +++++
 include/uapi/drm/drm.h      | 10 +++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index ca2a6e6101dc..5b1591e2b46c 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -302,6 +302,11 @@ 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_ATOMIC_ASYNC_PAGE_FLIP:
+		req->value = drm_core_check_feature(dev, DRIVER_ATOMIC) &&
+			     dev->mode_config.async_page_flip &&
+			     !dev->mode_config.atomic_async_page_flip_not_supported;
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 642808520d92..b1962628ecda 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -706,7 +706,8 @@ struct drm_gem_open {
 /**
  * DRM_CAP_ASYNC_PAGE_FLIP
  *
- * If set to 1, the driver supports &DRM_MODE_PAGE_FLIP_ASYNC.
+ * If set to 1, the driver supports &DRM_MODE_PAGE_FLIP_ASYNC for legacy
+ * page-flips.
  */
 #define DRM_CAP_ASYNC_PAGE_FLIP		0x7
 /**
@@ -767,6 +768,13 @@ struct drm_gem_open {
  * Documentation/gpu/drm-mm.rst, section "DRM Sync Objects".
  */
 #define DRM_CAP_SYNCOBJ_TIMELINE	0x14
+/**
+ * DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP
+ *
+ * If set to 1, the driver supports &DRM_MODE_PAGE_FLIP_ASYNC for atomic
+ * commits.
+ */
+#define DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP	0x15
 
 /* DRM_IOCTL_GET_CAP ioctl argument type */
 struct drm_get_cap {
-- 
2.37.2