netdev - Re: [PATCH net-next 2/2] igc: Add support for PTP .getcyclesx64()

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Date: Tue, 14 Nov 2023 20:19:45 +0100
From: Gerhard Engleder <gerhard@...leder-embedded.com>
To: Tony Nguyen <anthony.l.nguyen@...el.com>, davem@...emloft.net,
 kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com,
 netdev@...r.kernel.org
Cc: Vinicius Costa Gomes <vinicius.gomes@...el.com>, sasha.neftin@...el.com,
 richardcochran@...il.com, maciej.fijalkowski@...el.com,
 magnus.karlsson@...el.com, ast@...nel.org, daniel@...earbox.net,
 hawk@...nel.org, john.fastabend@...il.com, bpf@...r.kernel.org,
 Naama Meir <naamax.meir@...ux.intel.com>
Subject: Re: [PATCH net-next 2/2] igc: Add support for PTP .getcyclesx64()

On 14.11.23 19:36, Tony Nguyen wrote:
> From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> 
> Add support for using Timer 1 (i225/i226 have 4 timer registers) as a
> free-running clock (the "cycles" clock) in addition to Timer 0 (the
> default, "adjustable clock"). The objective is to allow taprio/etf
> offloading to coexist with PTP vclocks.
> 
> Besides the implementation of .getcyclesx64() for i225/i226, to keep
> timestamping working when vclocks are in use, we also need to add
> support for TX and RX timestamping using the free running timer, when
> the requesting socket is bound to a vclock.
> 
> On the RX side, i225/i226 can be configured to store the values of two
> timers in the received packet metadata area, so it's a matter of
> configuring the right registers and retrieving the right timestamp.
> 
> The TX is a bit more involved because the hardware stores a single
> timestamp (with the selected timer in the TX descriptor) into one of
> the timestamp registers.
> 
> Note some changes at how the timestamps are done for RX, the
> conversion and adjustment of timestamps are now done closer to the
> consumption of the timestamp instead of near the reception.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> Tested-by: Naama Meir <naamax.meir@...ux.intel.com>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
> ---
>   drivers/net/ethernet/intel/igc/igc.h         | 21 +++++++-
>   drivers/net/ethernet/intel/igc/igc_base.h    |  4 ++
>   drivers/net/ethernet/intel/igc/igc_defines.h |  2 +
>   drivers/net/ethernet/intel/igc/igc_main.c    | 55 ++++++++++++++------
>   drivers/net/ethernet/intel/igc/igc_ptp.c     | 50 +++++++++++-------
>   drivers/net/ethernet/intel/igc/igc_regs.h    |  5 ++
>   6 files changed, 101 insertions(+), 36 deletions(-)

I'm happy to see a second driver supporting this functionality!

Reviewed-by: Gerhard Engleder <gerhard@...leder-embedded.com>