PTP timer resolution on STM32MP2

[altsir_sga]

Hi,t

I am trying to understand maximum PTP clock frequency. On page 5122 of the STM32MP2 the maximal frequency defined as 100MHz, but on page 1037 (RCC section) the maximal clock frequency of clk_eth1_ptp_ref is 200MHz. Which one is correct? Can I have 200MHz PTP timer clock?

 

Another question, I am looking for a way to supply external clock for PTP timer, is there some way to do so?

 

Thanks!

Alexey.

[Christophe Guibout]

Hi @altsir_sga,

 

The max PTP clock is not 100MHz:

"The maximum PTP clock frequency is limited by the maximum resolution of the reference time (10 ns at 100 MHz)."

To confirm the max ptp clock is 200MHz, I cross-check on my STM23M257F-EV1 board:

cat /sys/kernel/debug/clk/clk_summary | grep ptp
   ck_ker_eth2ptp                   0       0        0        200000000   0          0     50000      N      deviceless                      no_connection_id
   ck_ker_eth1ptp                   0       0        0        200000000   0          0     50000      N      deviceless                      no_connection_id 

Hope it clarifies !

BR,

Christophe

[altsir_sga]

This great! Thanks!

 

What about my other question? Can you see any solution of clocking the PTP part by external clock?

 

Thanks!

Alexey.