[PATCH v6 4/6] drm/fence: add in-fences support

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>

There is now a new property called FENCE_FD attached to every plane
state that receives the sync_file fd from userspace via the atomic commit
IOCTL.

The fd is then translated to a fence (that may be a fence_collection
subclass or just a normal fence) and then used by DRM to fence_wait() for
all fences in the sync_file to signal. So it only commits when all
framebuffers are ready to scanout.

v2: Comments by Daniel Vetter:
	- remove set state->fence = NULL in destroy phase
	- accept fence -1 as valid and just return 0
	- do not call fence_get() - sync_file_fences_get() already calls it
	- fence_put() if state->fence is already set, in case userspace
	set the property more than once.

v3: WARN_ON if fence is set but state has no FB

v4: Comment from Maarten Lankhorst
	- allow set fence with no related fb

v5: rename FENCE_FD to IN_FENCE_FD

v6: Comments by Daniel Vetter:
	- rename plane_state->in_fence back to "fence"

     - rebase after fence -> dma_fence rename

Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
---
 drivers/gpu/drm/Kconfig             |  1 +
 drivers/gpu/drm/drm_atomic.c        | 15 +++++++++++++++
 drivers/gpu/drm/drm_atomic_helper.c |  5 +++--
 drivers/gpu/drm/drm_crtc.c          |  6 ++++++
 drivers/gpu/drm/drm_plane.c         |  1 +
 include/drm/drm_crtc.h              |  5 +++++
 6 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 483059a..43cb33d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -12,6 +12,7 @@ menuconfig DRM
 	select I2C
 	select I2C_ALGOBIT
 	select DMA_SHARED_BUFFER
+	select SYNC_FILE
 	help
 	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
 	  introduced in XFree86 4.0. If you say Y here, you need to select
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5e73954..28d9366 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -30,6 +30,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_mode.h>
 #include <drm/drm_plane_helper.h>
+#include <linux/sync_file.h>
 
 #include "drm_crtc_internal.h"
 
@@ -686,6 +687,17 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
 		drm_atomic_set_fb_for_plane(state, fb);
 		if (fb)
 			drm_framebuffer_unreference(fb);
+	} else if (property == config->prop_in_fence_fd) {
+		if (U642I64(val) == -1)
+			return 0;
+
+		if (state->fence)
+			dma_fence_put(state->fence);
+
+		state->fence = sync_file_get_fence(val);
+		if (!state->fence)
+			return -EINVAL;
+
 	} else if (property == config->prop_crtc_id) {
 		struct drm_crtc *crtc = drm_crtc_find(dev, val);
 		return drm_atomic_set_crtc_for_plane(state, crtc);
@@ -747,6 +759,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
 
 	if (property == config->prop_fb_id) {
 		*val = (state->fb) ? state->fb->base.id : 0;
+	} else if (property == config->prop_in_fence_fd) {
+		*val = -1;
 	} else if (property == config->prop_crtc_id) {
 		*val = (state->crtc) ? state->crtc->base.id : 0;
 	} else if (property == config->prop_crtc_x) {
@@ -1752,6 +1766,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 		drm_mode_object_unreference(obj);
 	}
 
+
 	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
 		for_each_crtc_in_state(state, crtc, crtc_state, i) {
 			struct drm_pending_vblank_event *e;
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 75ad01d..c34da9e 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1034,8 +1034,6 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
 		if (!plane_state->fence)
 			continue;
 
-		WARN_ON(!plane_state->fb);
-
 		/*
 		 * If waiting for fences pre-swap (ie: nonblock), userspace can
 		 * still interrupt the operation. Instead of blocking until the
@@ -3114,6 +3112,9 @@ void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
 {
 	if (state->fb)
 		drm_framebuffer_unreference(state->fb);
+
+	if (state->fence)
+		dma_fence_put(state->fence);
 }
 EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
 
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 13441e2..7878bfd 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -397,6 +397,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.prop_fb_id = prop;
 
+	prop = drm_property_create_signed_range(dev, DRM_MODE_PROP_ATOMIC,
+			"IN_FENCE_FD", -1, INT_MAX);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_in_fence_fd = prop;
+
 	prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
 			"CRTC_ID", DRM_MODE_OBJECT_CRTC);
 	if (!prop)
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 249c0ae..3957ef8 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -137,6 +137,7 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
 
 	if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
 		drm_object_attach_property(&plane->base, config->prop_fb_id, 0);
+		drm_object_attach_property(&plane->base, config->prop_in_fence_fd, -1);
 		drm_object_attach_property(&plane->base, config->prop_crtc_id, 0);
 		drm_object_attach_property(&plane->base, config->prop_crtc_x, 0);
 		drm_object_attach_property(&plane->base, config->prop_crtc_y, 0);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index fa1aa21..719b6a8 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1201,6 +1201,11 @@ struct drm_mode_config {
 	 */
 	struct drm_property *prop_fb_id;
 	/**
+	 * @prop_in_fence_fd: Sync File fd representing the incoming fences
+	 * for a Plane.
+	 */
+	struct drm_property *prop_in_fence_fd;
+	/**
 	 * @prop_crtc_id: Default atomic plane property to specify the
 	 * &drm_crtc.
 	 */
-- 
2.5.5