IEEE 1588v1 support by EMAC in AM335x.

Satoshi TOMINAGA

Other Parts Discussed in Thread: DP83640

Hi all,

I want to need the information about EMAC support of IEEE 1588v1 (not 1588v2).
I'm evaluating the clock synchronization using 1588v1. (for compatibility, 1588v2 cannot be used)

The platform is BBB, SDK v02.00.00.00.

When I execute ptp4l as slave-only in the network which the clock master exists,

root@am335x-evm:~# ptp4l -i eth0 -m -s -H

ptp4l[6060.535]: selected /dev/ptp0 as PTP clock
ptp4l[6060.545]: port 1: INITIALIZING to LISTENING on INITIALIZE
ptp4l[6060.547]: port 0: INITIALIZING to LISTENING on INITIALIZE
ptp4l[6068.519]: selected best master clock d05fb8.fffe.e44add
ptp4l[6075.998]: selected best master clock d05fb8.fffe.e44add

[ 7363.399227] cpts: unable to obtain a time stamp
[ 7371.427656] cpts: event pool is empty

The result of ethtool -T is follows:

root@am335x-evm:~# ethtool -T eth0
Time stamping parameters for eth0:
Capabilities:
hardware-transmit (SOF_TIMESTAMPING_TX_HARDWARE)
software-transmit (SOF_TIMESTAMPING_TX_SOFTWARE)
hardware-receive (SOF_TIMESTAMPING_RX_HARDWARE)
software-receive (SOF_TIMESTAMPING_RX_SOFTWARE)
software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
hardware-raw-clock (SOF_TIMESTAMPING_RAW_HARDWARE)
PTP Hardware Clock: 0
Hardware Transmit Timestamp Modes:
off (HWTSTAMP_TX_OFF)
on (HWTSTAMP_TX_ON)
Hardware Receive Filter Modes:
none (HWTSTAMP_FILTER_NONE)
ptpv2-event (HWTSTAMP_FILTER_PTP_V2_EVENT)

So, it seems that PHC subsystem for EMAC in AM335x does not support 1588v1.

Unfortunately I can't find detailed document about this issue.

Please let me know that EMAC in AM335x can support IEEE 1588v1 or not.

Regards,
TOMINAGA Satoshi

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

I will ask the Ethernet experts to comment.

0 Satoshi TOMINAGA over 8 years ago in reply to Biser Gatchev-XID

Intellectual 850 points

Hi Biser,

Thank you for your support.

FYI,

I've just find following in the kernel source of SDK v02.00.00.00.
In drivers/net/ethernet/ti/cpts.c:cpts_match()

if (unlikely(ptp_class & PTP_CLASS_V1))
msgtype = data + offset + OFF_PTP_CONTROL;
else
msgtype = data + offset;

This treat the PTPv1 packet.

But in drivers/net/ethernet/ti/cpsw.c:cpsw_hwtstamp_set()

switch (cfg.rx_filter) {
case HWTSTAMP_FILTER_NONE:
cpts->rx_enable = 0;
break;
case HWTSTAMP_FILTER_ALL:
case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
return -ERANGE;

This means ethtool can not set filter for PTPv1.

Regards,
TOMINAGA Satoshi

0 Satoshi TOMINAGA over 8 years ago in reply to Biser Gatchev-XID

Intellectual 850 points

Hi Biser,

I've just found the patch for CPTS PTP support .

www.spinics.net/.../msg213526.html

This patch includes PTPv1 support, but does not reflected to the current repository.
If this patch (to match the current repository, modifications are needed) can work properly with PTPv1, I want to try.

Please let me know that this patch really works for PTPv1 or not.
In the case of it works, I want to know why this patch does not included in the current repository.

Regards,
TOMINAGA Satoshi

0 Satoshi TOMINAGA over 8 years ago in reply to Satoshi TOMINAGA

Intellectual 850 points

Hi Biser,

Sorry that above patch does not support L4 PTP, both v1 and v2.

Regards,
TOMINAGA Satoshi

0 Satoshi TOMINAGA over 8 years ago in reply to Biser Gatchev-XID

Intellectual 850 points

Hi Biser,

Are there any progress on this issue?

I made quick hack to CPTS/CPSW source code to treat IEEE1588v1 packets.

Currently, it seems working for Sync and Follow_Up messages, but it is not clear for Delay_Request - Delay_Response packets.

So, I want to know the hardware specification of EMAC.

Is it able to support IEEE1588v1?

Is it possible to make support by software (kernel / firmware) modifications?

Regards,

TOMINAGA Satoshi

0 -DK- over 8 years ago in reply to Satoshi TOMINAGA

TI__Mastermind 27720 points

Tominaga-san,
The AM335x MAC only provides support for IEEE1588v2. IEEEv1 is not supported.

0 Satoshi TOMINAGA over 8 years ago in reply to -DK-

Intellectual 850 points

Hi -DK-,

Thank you for your reply.

I understand the specification of the MAC of AM335x.

I have one question about the combination of TI product.

From the datasheet, DP83640 supports the IEEE 1588v1 and it is indicated as PHC supported PHY in linuxptp.sourceforge.net/

With the combination of AM335x and DP83640, is IEEE 1588v1 hardware timestamping available by Linux SDK v02.00.00.00 or not?

Regards,

TOMINAGA Satoshi

0 Satoshi TOMINAGA over 8 years ago in reply to -DK-

Intellectual 850 points

Hi -DK-,

I found that AM335x MAC reports tx / rx hardware timestamps even IEEE 1588v1 is used.
But some fields are invalid when IEEE 1588v1, but not critical.

So, with some modification for kernel source, I can treat IEEE 1588v1 time synchronization with MAC timestamps.

Regards,
TOMINAGA Satoshi

0 Nick Saulnier over 4 years ago

TI__Guru 71795 points

Update: It looks like there was a typo in our documentation. AM335x supports IEEE 1588v1, not IEEE 1588v2. As of SDK 5.2, it looks like the Linux drivers for cpsw and cpts support 1588v1.

Processors

Processors forum

IEEE 1588v1 support by EMAC in AM335x.