[RFC v2 5/8] drm/fence: add in-fences support

From: Gustavo Padovan
Date: Mon Apr 25 2016 - 18:34:03 EST


From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

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.

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

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.
---
drivers/gpu/drm/Kconfig | 1 +
drivers/gpu/drm/drm_atomic.c | 14 ++++++++++++++
drivers/gpu/drm/drm_atomic_helper.c | 3 +++
drivers/gpu/drm/drm_crtc.c | 7 +++++++
include/drm/drm_crtc.h | 1 +
5 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index f2a74d0..3c987e3 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 8ee1db8..13674c7 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>

/**
* drm_atomic_state_default_release -
@@ -680,6 +681,17 @@ 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_fence_fd) {
+ if (U642I64(val) == -1)
+ return 0;
+
+ if (state->fence)
+ fence_put(state->fence);
+
+ state->fence = sync_file_fences_get(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);
@@ -737,6 +749,8 @@ 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_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) {
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index f1cfcce..866f332 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2696,6 +2696,9 @@ void __drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
{
if (state->fb)
drm_framebuffer_unreference(state->fb);
+
+ if (state->fence)
+ 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 55ffde5..65212ce 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1278,6 +1278,7 @@ 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_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);
@@ -1533,6 +1534,12 @@ 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,
+ "FENCE_FD", -1, INT_MAX);
+ if (!prop)
+ return -ENOMEM;
+ dev->mode_config.prop_fence_fd = prop;
+
prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
"CRTC_ID", DRM_MODE_OBJECT_CRTC);
if (!prop)
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 8cb377c..5ba3cda 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -2122,6 +2122,7 @@ struct drm_mode_config {
struct drm_property *prop_crtc_w;
struct drm_property *prop_crtc_h;
struct drm_property *prop_fb_id;
+ struct drm_property *prop_fence_fd;
struct drm_property *prop_crtc_id;
struct drm_property *prop_active;
struct drm_property *prop_mode_id;
--
2.5.5