dma-fence: Make ->enable_signaling optional

Many drivers have a trivial implementation for ->enable_signaling.
Let's make it optional by assuming that signalling is already
available when the callback isn't present.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-4-daniel.vetter@ffwll.ch

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 4edb9fd..7b5b40d 100644 (file)
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -181,6 +181,13 @@ void dma_fence_release(struct kref *kref)
 }
 EXPORT_SYMBOL(dma_fence_release);
 
+/**
+ * dma_fence_free - default release function for &dma_fence.
+ * @fence: fence to release
+ *
+ * This is the default implementation for &dma_fence_ops.release. It calls
+ * kfree_rcu() on @fence.
+ */
 void dma_fence_free(struct dma_fence *fence)
 {
        kfree_rcu(fence, rcu);
@@ -560,7 +567,7 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
               spinlock_t *lock, u64 context, unsigned seqno)
 {
        BUG_ON(!lock);
-       BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
+       BUG_ON(!ops || !ops->wait ||
               !ops->get_driver_name || !ops->get_timeline_name);
 
        kref_init(&fence->refcount);
@@ -572,6 +579,10 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
        fence->flags = 0UL;
        fence->error = 0;
 
+       if (!ops->enable_signaling)
+               set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
+                       &fence->flags);
+
        trace_dma_fence_init(fence);
 }
 EXPORT_SYMBOL(dma_fence_init);

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 111aefe..c053d19 100644 (file)
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -166,7 +166,8 @@ struct dma_fence_ops {
         * released when the fence is signalled (through e.g. the interrupt
         * handler).
         *
-        * This callback is mandatory.
+        * This callback is optional. If this callback is not present, then the
+        * driver must always have signaling enabled.
         */
        bool (*enable_signaling)(struct dma_fence *fence);