Re: [Linuxptp-users] Adding software-transmit (SOF_TIMESTAMPING_TX_SOFTWARE) capability to driver

[Keller, J. E <jac...@in...>]

> -----Original Message-----
> From: Miroslav Lichvar <mli...@re...>
> Sent: Wednesday, July 20, 2022 1:04 AM
> To: Richard Cochran <ric...@gm...>
> Cc: Keller, Jacob E <jac...@in...>; linuxptp-
> us...@li...
> Subject: Re: [Linuxptp-users] Adding software-transmit
> (SOF_TIMESTAMPING_TX_SOFTWARE) capability to driver
> 
> On Tue, Jul 19, 2022 at 09:02:37PM -0700, Richard Cochran wrote:
> > > I am not sure how accurate a software timestamp for a wifi device would
> > > be, given the potential delay between timestamp and actual transmission.
> >
> > WiFi on Linux is never going to support PTP.  The issue is the closed
> > source radio firmware.  End of story.
> 
> I tested driver TX timestamping in the mt76 driver, where the firmware
> is supposed to be very simple, but IIRC it didn't make a noticeable
> difference when compared to user-space TX timestamping.
> 
> But if there is demand, I think we could see wireless chips with
> HW-timestamping support in future. If the stations can hear each
> other, maybe it wouldn't even be necessary for the access point to
> support PTP, like when using a cheap Ethernet hub instead of expensive
> switch with PTP support.
> 
> --
> Miroslav Lichvar

Right that's what I was afraid of: its basically just the same as software timestamping.

Thanks,
Jake