26.01.2021 05:45, Mikko Perttunen пишет:
- The hardware state of sync points should be reset when sync point is
requested, not when host1x driver is initialized.
This may be doable, but I don't think it is critical for this UAPI, so let's consider it after this series.
The userspace should anyway not be able to assume the initial value of the syncpoint upon allocation. The kernel should set it to some high value to catch any issues related to wraparound.
This is critical because min != max when sync point is requested.
Also, this makes code more complicated since it now needs to ensure all waits on the syncpoint have completed before freeing the syncpoint, which can be nontrivial e.g. if the waiter is in a different virtual machine or some other device connected via PCIe (a real usecase).
It sounds to me that these VM sync points should be treated very separately from a generic sync points, don't you think so? Let's not mix them and get the generic sync points usable first.