[RFC v2 03/13] dma-fence: Use a flag for 64-bit seqnos

[Tvrtko Ursulin]

With the goal of reducing the need for drivers to touch (and dereference)
fence->ops, we move the 64-bit seqnos flag from struct dma_fence_ops to
the fence->flags.

Drivers which were setting this flag are changed to use new
dma_fence_init64() instead of dma_fence_init().

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
---
 drivers/dma-buf/dma-fence-chain.c                | 5 ++---
 drivers/dma-buf/dma-fence.c                      | 9 +++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c | 5 ++---
 include/linux/dma-fence.h                        | 6 +++++-
 4 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-chain.c b/drivers/dma-buf/dma-fence-chain.c
index 90424f23fd73..a8a90acf4f34 100644
--- a/drivers/dma-buf/dma-fence-chain.c
+++ b/drivers/dma-buf/dma-fence-chain.c
@@ -218,7 +218,6 @@ static void dma_fence_chain_set_deadline(struct dma_fence *fence,
 }
 
 const struct dma_fence_ops dma_fence_chain_ops = {
-	.use_64bit_seqno = true,
 	.get_driver_name = dma_fence_chain_get_driver_name,
 	.get_timeline_name = dma_fence_chain_get_timeline_name,
 	.enable_signaling = dma_fence_chain_enable_signaling,
@@ -262,8 +261,8 @@ void dma_fence_chain_init(struct dma_fence_chain *chain,
 			seqno = max(prev->seqno, seqno);
 	}
 
-	dma_fence_init(&chain->base, &dma_fence_chain_ops,
-		       &chain->lock, context, seqno);
+	dma_fence_init64(&chain->base, &dma_fence_chain_ops, &chain->lock,
+			 context, seqno);
 
 	/*
 	 * Chaining dma_fence_chain container together is only allowed through
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index f0cdd3e99d36..33661658f684 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -1023,3 +1023,12 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 	trace_dma_fence_init(fence);
 }
 EXPORT_SYMBOL(dma_fence_init);
+
+void
+dma_fence_init64(struct dma_fence *fence, const struct dma_fence_ops *ops,
+		 spinlock_t *lock, u64 context, u64 seqno)
+{
+	dma_fence_init(fence, ops, lock, context, seqno);
+	__set_bit(DMA_FENCE_FLAG_SEQNO64_BIT, &fence->flags);
+}
+EXPORT_SYMBOL(dma_fence_init64);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
index 51cddfa3f1e8..5d26797356a3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
@@ -71,7 +71,6 @@ static void amdgpu_tlb_fence_work(struct work_struct *work)
 }
 
 static const struct dma_fence_ops amdgpu_tlb_fence_ops = {
-	.use_64bit_seqno = true,
 	.get_driver_name = amdgpu_tlb_fence_get_driver_name,
 	.get_timeline_name = amdgpu_tlb_fence_get_timeline_name
 };
@@ -101,8 +100,8 @@ void amdgpu_vm_tlb_fence_create(struct amdgpu_device *adev, struct amdgpu_vm *vm
 	INIT_WORK(&f->work, amdgpu_tlb_fence_work);
 	spin_lock_init(&f->lock);
 
-	dma_fence_init(&f->base, &amdgpu_tlb_fence_ops, &f->lock,
-		       vm->tlb_fence_context, atomic64_read(&vm->tlb_seq));
+	dma_fence_init64(&f->base, &amdgpu_tlb_fence_ops, &f->lock,
+			 vm->tlb_fence_context, atomic64_read(&vm->tlb_seq));
 
 	/* TODO: We probably need a separate wq here */
 	dma_fence_get(&f->base);
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 48b5202c531d..ac6535716dbe 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -97,6 +97,7 @@ struct dma_fence {
 };
 
 enum dma_fence_flag_bits {
+	DMA_FENCE_FLAG_SEQNO64_BIT,
 	DMA_FENCE_FLAG_SIGNALED_BIT,
 	DMA_FENCE_FLAG_TIMESTAMP_BIT,
 	DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
@@ -262,6 +263,9 @@ struct dma_fence_ops {
 void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 		    spinlock_t *lock, u64 context, u64 seqno);
 
+void dma_fence_init64(struct dma_fence *fence, const struct dma_fence_ops *ops,
+		      spinlock_t *lock, u64 context, u64 seqno);
+
 void dma_fence_release(struct kref *kref);
 void dma_fence_free(struct dma_fence *fence);
 void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq);
@@ -454,7 +458,7 @@ static inline bool __dma_fence_is_later(struct dma_fence *fence, u64 f1, u64 f2)
 	 * 32bit sequence numbers. Use a 64bit compare when the driver says to
 	 * do so.
 	 */
-	if (fence->ops->use_64bit_seqno)
+	if (test_bit(DMA_FENCE_FLAG_SEQNO64_BIT, &fence->flags))
 		return f1 > f2;
 
 	return (int)(lower_32_bits(f1) - lower_32_bits(f2)) > 0;
-- 
2.48.0