Commit ce04ec03 authored by Akash Goel's avatar Akash Goel Committed by Boris Brezillon
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drm/panthor: Avoid adding of kernel BOs to extobj list 



The kernel BOs unnecessarily got added to the external objects list
of drm_gpuvm, when mapping to GPU, which would have resulted in few
extra CPU cycles being spent at the time of job submission as
drm_exec_until_all_locked() loop iterates over all external objects.

Kernel BOs are private to a VM and so they share the dma_resv object of
the dummy GEM object created for a VM. Use of DRM_EXEC_IGNORE_DUPLICATES
flag ensured the recursive locking of the dummy GEM object was ignored.
Also no extra space got allocated to add fences to the dma_resv object
of dummy GEM object. So no other impact apart from few extra CPU cycles.

This commit sets the pointer to dma_resv object of GEM object of
kernel BOs before they are mapped to GPU, to prevent them from
being added to external objects list.

v2: Add R-bs and fixes tags

Fixes: 8a1cc075 ("drm/panthor: Add GEM logical block")
Signed-off-by: default avatarAkash Goel <akash.goel@arm.com>
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20251120172118.2741724-1-akash.goel@arm.com


Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
parent 63c971af

drivers/gpu/drm/panthor/panthor_gem.c

+3 −3
Original line number Diff line number Diff line
@@ -145,6 +145,9 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, 
	bo = to_panthor_bo(&obj->base);

	kbo->obj = &obj->base;

	bo->flags = bo_flags;

	bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm);

	drm_gem_object_get(bo->exclusive_vm_root_gem);

	bo->base.base.resv = bo->exclusive_vm_root_gem->resv;



	if (vm == panthor_fw_vm(ptdev))

		debug_flags |= PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED;
@@ -168,9 +171,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, 
		goto err_free_va;



	kbo->vm = panthor_vm_get(vm);

	bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm);

	drm_gem_object_get(bo->exclusive_vm_root_gem);

	bo->base.base.resv = bo->exclusive_vm_root_gem->resv;

	return kbo;



err_free_va: