[RFC 8/8] drm/fence: add out-fences support

From: Gustavo Padovan
Date: Thu Apr 14 2016 - 21:30:02 EST

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

Support DRM out-fences creating a sync_file with a fence for each crtc
update with the DRM_MODE_ATOMIC_OUT_FENCE flag.

We then send an struct drm_out_fences array with the out-fences fds back in
the drm_atomic_ioctl() as an out arg in the out_fences_ptr field.

struct drm_out_fences {
__u32 crtc_id;
__u32 fd;
};

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic.c | 109 +++++++++++++++++++++++++++++++++++-
drivers/gpu/drm/drm_atomic_helper.c | 1 +
include/drm/drm_crtc.h | 3 +
include/uapi/drm/drm_mode.h | 7 +++
4 files changed, 119 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 0b95526..af6e051 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1560,6 +1560,103 @@ void drm_atomic_clean_old_fb(struct drm_device *dev,
}
EXPORT_SYMBOL(drm_atomic_clean_old_fb);

+static int drm_atomic_get_out_fences(struct drm_device *dev,
+ struct drm_atomic_state *state,
+ uint32_t __user *out_fences_ptr,
+ uint64_t count_out_fences,
+ uint64_t user_data)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ struct drm_out_fences *out_fences;
+ struct sync_file **sync_file;
+ int num_fences = 0;
+ int i, ret;
+
+ out_fences = kcalloc(count_out_fences, sizeof(*out_fences),
+ GFP_KERNEL);
+ if (!out_fences)
+ return -ENOMEM;
+
+ sync_file = kcalloc(count_out_fences, sizeof(*sync_file),
+ GFP_KERNEL);
+ if (!sync_file) {
+ kfree(out_fences);
+ return -ENOMEM;
+ }
+
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ struct drm_pending_vblank_event *e;
+ struct fence *fence;
+ char name[32];
+ int fd;
+
+ fence = sync_timeline_create_fence(crtc->timeline,
+ crtc->fence_seqno);
+ if (!fence) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ snprintf(name, sizeof(name), "crtc-%d_%lu",
+ drm_crtc_index(crtc), crtc->fence_seqno++);
+
+ sync_file[i] = sync_file_create(name, fence);
+ if(!sync_file[i]) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0) {
+ ret = fd;
+ goto out;
+ }
+
+ sync_file_install(sync_file[i], fd);
+
+ if (crtc_state->event) {
+ crtc_state->event->base.fence = fence;
+ } else {
+ e = create_vblank_event(dev, NULL, fence, user_data);
+ if (!e) {
+ put_unused_fd(fd);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ crtc_state->event = e;
+ }
+ if (num_fences > count_out_fences) {
+ put_unused_fd(fd);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ fence_get(fence);
+
+ out_fences[num_fences].crtc_id = crtc->base.id;
+ out_fences[num_fences].fd = fd;
+ num_fences++;
+ }
+
+ if (copy_to_user(out_fences_ptr, out_fences,
+ num_fences * sizeof(*out_fences))) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ return 0;
+
+out:
+ for (i = 0 ; i < count_out_fences ; i++) {
+ if (sync_file[i])
+ sync_file_put(sync_file[i]);
+ }
+
+ return ret;
+}
+
int drm_mode_atomic_ioctl(struct drm_device *dev,
void *data, struct drm_file *file_priv)
{
@@ -1568,6 +1665,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
uint32_t __user *count_props_ptr = (uint32_t __user *)(unsigned long)(arg->count_props_ptr);
uint32_t __user *props_ptr = (uint32_t __user *)(unsigned long)(arg->props_ptr);
uint64_t __user *prop_values_ptr = (uint64_t __user *)(unsigned long)(arg->prop_values_ptr);
+ uint32_t __user *out_fences_ptr = (uint32_t __user *)(unsigned long)(arg->out_fences_ptr);
unsigned int copied_objs, copied_props;
struct drm_atomic_state *state;
struct drm_modeset_acquire_ctx ctx;
@@ -1601,7 +1699,8 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,

/* can't test and expect an event at the same time. */
if ((arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) &&
- (arg->flags & DRM_MODE_PAGE_FLIP_EVENT))
+ (arg->flags & (DRM_MODE_PAGE_FLIP_EVENT
+ | DRM_MODE_ATOMIC_OUT_FENCE)))
return -EINVAL;

drm_modeset_acquire_init(&ctx, 0);
@@ -1693,6 +1792,14 @@ retry:
}
}

+ if (arg->flags & DRM_MODE_ATOMIC_OUT_FENCE) {
+ ret = drm_atomic_get_out_fences(dev, state, out_fences_ptr,
+ arg->count_out_fences,
+ arg->user_data);
+ if (ret < 0)
+ goto out;
+ }
+
if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
/*
* Unlike commit, check_only does not clean up state.
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 6ed8339..15ba3a8 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -31,6 +31,7 @@
#include <drm/drm_crtc_helper.h>
#include <drm/drm_atomic_helper.h>
#include <linux/fence.h>
+#include <linux/sync_file.h>

/**
* DOC: overview
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 7934178..53e4e71 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -717,6 +717,7 @@ struct drm_crtc_funcs {
* @properties: property tracking for this CRTC
* @state: current atomic state for this CRTC
* @timeline: sync timeline for fence sigalling
+ * @fence_seqno: seqno variable to create fences
* @acquire_ctx: per-CRTC implicit acquire context used by atomic drivers for
* legacy IOCTLs
*
@@ -773,7 +774,9 @@ struct drm_crtc {

struct drm_crtc_state *state;

+ /* for out-fences */
struct sync_timeline *timeline;
+ unsigned long fence_seqno;

/*
* For legacy crtc IOCTLs so that atomic drivers can get at the locking
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 39905cc..4cdcd22 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -592,6 +592,11 @@ struct drm_mode_destroy_dumb {
DRM_MODE_ATOMIC_ALLOW_MODESET |\
DRM_MODE_ATOMIC_OUT_FENCE)

+struct drm_out_fences {
+ __u32 crtc_id;
+ __u32 fd;
+};
+
struct drm_mode_atomic {
__u32 flags;
__u32 count_objs;
@@ -601,6 +606,8 @@ struct drm_mode_atomic {
__u64 prop_values_ptr;
__u64 reserved;
__u64 user_data;
+ __u64 count_out_fences;
+ __u64 out_fences_ptr;
};

/**
--
2.5.5