Re: [PATCH net-next v4 6/8] net: dsa: microchip: Enable Ethernet PTP detection

[Bastien Curutchet <bastien.curutchet@bootlin.com>]

Hi,

On 1/30/26 6:16 AM, Tristram.Ha@microchip.com wrote:
>> On Tue, 27 Jan 2026 10:06:48 +0100 Bastien Curutchet (Schneider
>> Electric) wrote:
>>> KSZ8463 needs to enable the Ethernet PTP detection to fire the
>>> interrupts when a timestamp is captured.
>>
>> Is it worth stating our expectation WRT other switches given this
>> is a shared function (not advocating to add a condition to be clear,
>> just document).

The PTP_ETH_ENABLE bit added here is already set by default on the 
'second generation' switches Tristram mentioned but not on the KSZ8463. 
I'll add details to the commit log.

> 
> KSZ8464 uses the first generation of PTP engine while KSZ9477/KSZ9567 and
> LAN937X use the second generation.  Most of their basic operations like
> transmitting are the same.  KSZ8463 enables 1-step E2E TC operation by
> default while the newer switches need to enable the function manually.
> Because of that the PTP function in KSZ8463 is disabled after driver
> starts until the Linux PTP stack wants to enable the feature.
> 

I think that here you refer to the PTP_ENABLE bit. It's indeed unset at 
init in ksz8_config_cpu_port() but it's then set back by 
ksz_ptp_enable_mode() when needed.

PTP_ETH_ENABLE (bit 5) enables detection of L2 PTP frames
PTP_ENABLE (bit 6) enables the full PTP feature.


Best regards,
Bastien