On Mon, Dec 31, 2018 at 8:52 PM Yong Wu [off-list ref] wrote:

The iommu consumer should use device_link to connect with the
smi-larb(supplier). then the smi-larb should run before the iommu
consumer. Here we delay the iommu driver until the smi driver is
ready, then all the iommu consumer always is after the smi driver.

When there is no this patch, if some consumer drivers run before
smi-larb, the supplier link_status is DL_DEV_NO_DRIVER(0) in the
device_link_add, then device_links_driver_bound will use WARN_ON
to complain that the link_status of supplier is not right.

I don't quite have enough knowledge of device links to figure out if
this is a) the right fix, b) a deficiency in the device_links code, or
c) neither.

Perhaps someone else could chime in on this one.
-Evan

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