Re: [PATCH net-next 0/3] ice: lighter locking for PTP time reading

[Jacob Keller <jacob.e.keller@intel.com>]

On 2/26/2024 7:11 AM, Michal Schmidt wrote:
> This series removes the use of the heavy-weight PTP hardware semaphore
> in the gettimex64 path. Instead, serialization of access to the time
> register is done using a host-side spinlock. The timer hardware is
> shared between PFs on the PCI adapter, so the spinlock must be shared
> between ice_pf instances too.
> 
> Michal Schmidt (3):
>   ice: add ice_adapter for shared data across PFs on the same NIC
>   ice: avoid the PTP hardware semaphore in gettimex64 path
>   ice: fold ice_ptp_read_time into ice_ptp_gettimex64
> 

Glad to see some fix and improvement in this place. I had been
considering switching the hardware semaphore entirely to be a shared
mutex instead, but this direction also seems reasonable and fixes most
of the issues. We could actually extend this to replace the semaphore
with a mutex in order to avoid the PCIe transactions required to handle
the hardware semaphore register.