[PATCH 01/10] iommu: Remove useless group refcounting

[Tian, Kevin]

> From: Jason Gunthorpe <jgg at nvidia.com>
> Sent: Wednesday, July 19, 2023 3:06 AM
>
>  int iommu_device_use_default_domain(struct device *dev)
>  {
> -	struct iommu_group *group = iommu_group_get(dev);
> +	/* Caller must be a probed driver on dev */
> +	struct iommu_group *group = dev->iommu_group;
>  	int ret = 0;

this is called in the probing path by .dma_configure().

the driver hasn't been probed yet hence the rationale to not
refcount is due to device_lock() instead?