[PATCH v2] drm/amdgpu: Refactor amdgpu_gem_va_ioctl for Handling Last Fence Update and Timeline Management v2

[Srinivasan Shanmugam]

This commit simplifies the amdgpu_gem_va_ioctl function, key updates
include:
 - Moved the logic for managing the last update fence directly into
   amdgpu_gem_va_update_vm.
 - Introduced checks for the timeline point to enable conditional
   replacement or addition of fences.

v2: Addressed review comments from Christian.

Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Christian König <christian.koenig at amd.com>
Suggested-by: Christian König <christian.koenig at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 82 +++++++++----------------
 1 file changed, 30 insertions(+), 52 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 2c68118fe9fd..aea0c63e441a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -112,47 +112,6 @@ amdgpu_gem_update_timeline_node(struct drm_file *filp,
 	return 0;
 }
 
-static void
-amdgpu_gem_update_bo_mapping(struct drm_file *filp,
-			     struct amdgpu_bo_va *bo_va,
-			     uint32_t operation,
-			     uint64_t point,
-			     struct dma_fence *fence,
-			     struct drm_syncobj *syncobj,
-			     struct dma_fence_chain *chain)
-{
-	struct amdgpu_bo *bo = bo_va ? bo_va->base.bo : NULL;
-	struct amdgpu_fpriv *fpriv = filp->driver_priv;
-	struct amdgpu_vm *vm = &fpriv->vm;
-	struct dma_fence *last_update;
-
-	if (!syncobj)
-		return;
-
-	/* Find the last update fence */
-	switch (operation) {
-	case AMDGPU_VA_OP_MAP:
-	case AMDGPU_VA_OP_REPLACE:
-		if (bo && (bo->tbo.base.resv == vm->root.bo->tbo.base.resv))
-			last_update = vm->last_update;
-		else
-			last_update = bo_va->last_pt_update;
-		break;
-	case AMDGPU_VA_OP_UNMAP:
-	case AMDGPU_VA_OP_CLEAR:
-		last_update = fence;
-		break;
-	default:
-		return;
-	}
-
-	/* Add fence to timeline */
-	if (!point)
-		drm_syncobj_replace_fence(syncobj, last_update);
-	else
-		drm_syncobj_add_point(syncobj, chain, last_update, point);
-}
-
 static vm_fault_t amdgpu_gem_fault(struct vm_fault *vmf)
 {
 	struct ttm_buffer_object *bo = vmf->vma->vm_private_data;
@@ -780,6 +739,12 @@ amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
 		r = amdgpu_vm_bo_update(adev, bo_va, false);
 		if (r)
 			goto error;
+
+		/* Set the last_update fence based on the operation */
+		if (amdgpu_vm_is_bo_always_valid(vm, bo_va->base.bo))
+			fence = vm->last_update; /* Use VM's last update fence */
+		else
+			fence = bo_va->last_pt_update; /* Use buffer object's last update fence */
 	}
 
 	r = amdgpu_vm_update_pdes(adev, vm, false);
@@ -845,6 +810,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 	uint64_t vm_size;
 	int r = 0;
 
+	/* Validate virtual address */
 	if (args->va_address < AMDGPU_VA_RESERVED_BOTTOM) {
 		dev_dbg(dev->dev,
 			"va_address 0x%llx is in reserved area 0x%llx\n",
@@ -878,6 +844,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 		return -EINVAL;
 	}
 
+	/* Operational check */
 	switch (args->operation) {
 	case AMDGPU_VA_OP_MAP:
 	case AMDGPU_VA_OP_UNMAP:
@@ -901,6 +868,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 		abo = NULL;
 	}
 
+	/* Add input fence for synchronization */
 	r = amdgpu_gem_add_input_fence(filp,
 				       args->input_fence_syncobj_handles,
 				       args->num_syncobj_handles);
@@ -923,6 +891,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 			goto error;
 	}
 
+	/* Find buffer object virtual address */
 	if (abo) {
 		bo_va = amdgpu_vm_bo_find(&fpriv->vm, abo);
 		if (!bo_va) {
@@ -935,6 +904,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 		bo_va = NULL;
 	}
 
+	/* Update timeline node for synchronization */
 	r = amdgpu_gem_update_timeline_node(filp,
 					    args->vm_timeline_syncobj_out,
 					    args->vm_timeline_point,
@@ -943,6 +913,10 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 	if (r)
 		goto error;
 
+	/* Call to update VM and retrieve the resulting fence */
+	fence = amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
+					args->operation);
+
 	switch (args->operation) {
 	case AMDGPU_VA_OP_MAP:
 		va_flags = amdgpu_gem_va_map_flags(adev, args->flags);
@@ -968,19 +942,23 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
 	default:
 		break;
 	}
+
 	if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) && !adev->debug_vm) {
-		fence = amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
-						args->operation);
-
-		if (timeline_syncobj)
-			amdgpu_gem_update_bo_mapping(filp, bo_va,
-					     args->operation,
-					     args->vm_timeline_point,
-					     fence, timeline_syncobj,
-					     timeline_chain);
-		else
+		if (timeline_syncobj) {
+			if (!args->vm_timeline_point) {
+				/* Replace the existing fence if point is not set */
+				drm_syncobj_replace_fence(timeline_syncobj,
+							  fence);
+			} else {
+				/* Add last update fence at a specific timeline point */
+				drm_syncobj_add_point(timeline_syncobj,
+						      timeline_chain,
+						      fence,
+						      args->vm_timeline_point);
+			}
+		} else {
 			dma_fence_put(fence);
-
+		}
 	}
 
 error:
-- 
2.34.1