[PATCH v4 11/30] drm/xe: Move setting last fence to vm_bind_ioctl_ops_install_fences

[Zeng, Oak]

> -----Original Message-----
> From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of Matthew
> Brost
> Sent: Friday, March 8, 2024 12:08 AM
> To: intel-xe at lists.freedesktop.org
> Cc: Brost, Matthew <matthew.brost at intel.com>
> Subject: [PATCH v4 11/30] drm/xe: Move setting last fence to
> vm_bind_ioctl_ops_install_fences
> 
> This moves setting of the last fence to a single location.
> 
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vm.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 8c96c98cba37..4432531f39fe 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -1841,9 +1841,6 @@ xe_vm_bind(struct xe_vm *vm, struct xe_vma *vma,
> struct xe_exec_queue *q,
>  		fence = xe_exec_queue_last_fence_get(wait_exec_queue, vm);
>  	}
> 
> -	if (last_op)
> -		xe_exec_queue_last_fence_set(wait_exec_queue, vm, fence);
> -
>  	return fence;
>  }
> 
> @@ -1853,7 +1850,6 @@ xe_vm_unbind(struct xe_vm *vm, struct xe_vma *vma,
>  	     u32 num_syncs, bool first_op, bool last_op)
>  {
>  	struct dma_fence *fence;
> -	struct xe_exec_queue *wait_exec_queue = to_wait_exec_queue(vm,
> q);
> 
>  	xe_vm_assert_held(vm);
>  	xe_bo_assert_held(xe_vma_bo(vma));
> @@ -1862,9 +1858,6 @@ xe_vm_unbind(struct xe_vm *vm, struct xe_vma *vma,
>  	if (IS_ERR(fence))
>  		return fence;
> 
> -	if (last_op)
> -		xe_exec_queue_last_fence_set(wait_exec_queue, vm, fence);
> -
>  	return fence;
>  }
> 
> @@ -2820,6 +2813,7 @@ static void vm_bind_ioctl_ops_install_fences(struct
> xe_vm *vm,
>  					     struct xe_vma_ops *vops,
>  					     struct dma_fence *fence)
>  {
> +	struct xe_exec_queue *wait_exec_queue = to_wait_exec_queue(vm,
> vops->q);
>  	struct xe_vma_op *op;
>  	int i;
> 
> @@ -2832,6 +2826,7 @@ static void vm_bind_ioctl_ops_install_fences(struct
> xe_vm *vm,
>  	}
>  	for (i = 0; i < vops->num_syncs; i++)
>  		xe_sync_entry_signal(vops->syncs + i, NULL, fence);
> +	xe_exec_queue_last_fence_set(wait_exec_queue, vm, fence);


Oh, With this patch, I can understand the dma-fence-put below won't destroy the last fence, because this fence is set to exec queue's last fence.

I also understand now, how the last fence will be used to signal the out-fences of vm_bind ioctl... things make sense to me now...

IMO, maybe you can squash this patch to the last patch, so people don't have the confusion as I had.

Oak
>  	dma_fence_put(fence);
>  }
> 
> --
> 2.34.1