Revert 190c462d5be19ba622a82f5fd0625087c870a1e6..bf3012ada1b2222e770de5c35c1bb16f73b3a01d"

I shouldn't have pushed this, CI was right - I failed to remove the
BUG_ON(!ops->wait);

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 02dba8cd033d..eb9b05aa5aea 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -166,8 +166,7 @@ struct dma_fence_ops {
 	 * released when the fence is signalled (through e.g. the interrupt
 	 * handler).
 	 *
-	 * This callback is optional. If this callback is not present, then the
-	 * driver must always have signaling enabled.
+	 * This callback is mandatory.
 	 */
 	bool (*enable_signaling)(struct dma_fence *fence);
 
@@ -191,14 +190,11 @@ struct dma_fence_ops {
 	/**
 	 * @wait:
 	 *
-	 * Custom wait implementation, defaults to dma_fence_default_wait() if
-	 * not set.
+	 * Custom wait implementation, or dma_fence_default_wait.
 	 *
-	 * The dma_fence_default_wait implementation should work for any fence, as long
-	 * as @enable_signaling works correctly. This hook allows drivers to
-	 * have an optimized version for the case where a process context is
-	 * already available, e.g. if @enable_signaling for the general case
-	 * needs to set up a worker thread.
+	 * Must not be NULL, set to dma_fence_default_wait for default implementation.
+	 * the dma_fence_default_wait implementation should work for any fence, as long
+	 * as enable_signaling works correctly.
 	 *
 	 * Must return -ERESTARTSYS if the wait is intr = true and the wait was
 	 * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
@@ -206,7 +202,7 @@ struct dma_fence_ops {
 	 * which should be treated as if the fence is signaled. For example a hardware
 	 * lockup could be reported like that.
 	 *
-	 * This callback is optional.
+	 * This callback is mandatory.
 	 */
 	signed long (*wait)(struct dma_fence *fence,
 			    bool intr, signed long timeout);
@@ -222,6 +218,17 @@ struct dma_fence_ops {
 	void (*release)(struct dma_fence *fence);
 
 	/**
+	 * @fill_driver_data:
+	 *
+	 * Callback to fill in free-form debug info.
+	 *
+	 * Returns amount of bytes filled, or negative error on failure.
+	 *
+	 * This callback is optional.
+	 */
+	int (*fill_driver_data)(struct dma_fence *fence, void *data, int size);
+
+	/**
 	 * @fence_value_str:
 	 *
 	 * Callback to fill in free-form debug info specific to this fence, like
@@ -235,9 +242,8 @@ struct dma_fence_ops {
 	 * @timeline_value_str:
 	 *
 	 * Fills in the current value of the timeline as a string, like the
-	 * sequence number. Note that the specific fence passed to this function
-	 * should not matter, drivers should only use it to look up the
-	 * corresponding timeline structures.
+	 * sequence number. This should match what @fill_driver_data prints for
+	 * the most recently signalled fence (assuming no delayed signalling).
 	 */
 	void (*timeline_value_str)(struct dma_fence *fence,
 				   char *str, int size);