fence = dma_resv_get_excl_rcu(obj->resv); drm_atomic_set_fence_for_plane(state, fence); return 0; } 在KMS的atomic操作中,会等待独占dma-fence被signal,代码如下: int drm_atomic_helper_wait_for_fences(struct drm_device *dev, struct drm_atomic_state *state, bool pre_swap) { struct drm...
一个被初始化的dma-fence,使用wait函数后,会将当前进程换出,即当前进程会sleep,而当调用signal函数时会唤醒被wait函数换出的进程。 dma-fence的使用还可以通过向dma-fence添加一个或多个callback函数,当dma-fence调用signal操作时,会依次遍历callback list,并调用每个callback函数。当调用wait函数时,会把默认的一个...
fence = dma_resv_get_excl_rcu(obj->resv);drm_atomic_set_fence_for_plane(state, fence); return 0; } 在KMS的atomic操作中,会等待独占dma-fence被signal,代码如下: int drm_atomic_helper_wait_for_fences(struct drm_device *dev, struct drm_atomic_state *state, bool pre_swap) { struct drm_...
cookie = dma_fence_begin_signalling();lock(A);unlock(A);dma_fence_signal(B);dma_fence_end_signalling(cookie); 为了使用 dma_fence_begin_signalling() 和 dma_fence_end_signalling() 注释关键部分,需要遵守以下规则: 必须注释完成 dma_fence 所需的所有代码,从栅栏对其他线程可访问的点到调用 dma_fen...
Expand Up@@ -312,22 +312,25 @@ void __dma_fence_might_wait(void) /** *dma_fence_signal_locked- signal completion of a fence *dma_fence_signal_timestamp_locked- signal completion of a fence * @fence: the fence to signal * @timestamp: fence signal timestamp in kernel's CLOCK_MONO...
为了支持缓冲区访问的跨设备和跨驱动程序同步,可以将隐式fence(在内核中用struct dma_fence表示)附加到dma_buf上。dma_resv结构提供了这方面的支持。 用户空间可以使用poll()和相关的系统调用来查询这些隐式跟踪的fence的状态: 检查EPOLLIN,即读访问,可以用来查询最近写入或独占fence的状态。
* (since it has to wait an additional vblank period), sending a signal to * the GPU's devfreq to reduce frequency, when in fact the opposite is what is * needed. * * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline. * The deadline hint...
May return -EINTR if it is interrupted by a signal. * * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that * the underlying backing storage is pinned for as long as a mapping exists, * therefore users/importers should not hold onto a mapping for undue amounts ...
run_job:一旦job的所有依赖项变得可用后,会调用该接口。这个接口主要是实现GPU HW相关的命令提交。该接口成功把命令提交到GPU上后,返回一个dma_fence,gpu scheduler会向这个dma_fence的callback list中添加finish fence唤醒操作,而这个dma_fence一般会在GPU处理完毕该job后被signal。
Fence可以实现不同模块的动态通知、唤醒,从而实现模块间任务的动态调度。这样模块间的任务不再是静态写死的 A—>B—>C, 可以动态设置fence dependency,当fence条件满足后即可动态调度等待这个fence的任务。 什么时候会trigger一次fence signal? 比如,某个node process done,某个硬件process done等,都可以通知等待这个fe...