Re: [PATCH net] net: ethernet: ti: am65-cpts: Fix PTPv1 message type on TX packets

[Jason Reeder <jreeder@ti.com>]

On 4/19/24 02:05, Ravi Gunasekaran wrote:
> From: Jason Reeder <jreeder@ti.com>
> 
> The CPTS, by design, captures the messageType (Sync, Delay_Req, etc.)
> field from the second nibble of the PTP header which is defined in the
> PTPv2 (1588-2008) specification. In the PTPv1 (1588-2002) specification
> the first two bytes of the PTP header are defined as the versionType
> which is always 0x0001. This means that any PTPv1 packets that are
> tagged for TX timestamping by the CPTS will have their messageType set
> to 0x0 which corresponds to a Sync message type. This causes issues
> when a PTPv1 stack is expecting a Delay_Req (messageType: 0x1)
> timestamp that never appears.
> 
> Fix this by checking if the ptp_class of the timestamped TX packet is
> PTP_CLASS_V1 and then matching the PTP sequence ID to the stored
> sequence ID in the skb->cb data structure. If the sequence IDs match
> and the packet is of type PTPv1 then there is a chance that the
> messageType has been incorrectly stored by the CPTS so overwrite the
> messageType stored by the CPTS with the messageType from the skb->cb
> data structure. This allows the PTPv1 stack to receive TX timestamps
> for Delay_Req packets which are necessary to lock onto a PTP Leader.
> 
> Signed-off-by: Jason Reeder <jreeder@ti.com>
> Signed-off-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
> ---
>   drivers/net/ethernet/ti/am65-cpts.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/ethernet/ti/am65-cpts.c b/drivers/net/ethernet/ti/am65-cpts.c
> index c66618d91c28..f89716b1cfb6 100644
> --- a/drivers/net/ethernet/ti/am65-cpts.c
> +++ b/drivers/net/ethernet/ti/am65-cpts.c
> @@ -784,6 +784,11 @@ static bool am65_cpts_match_tx_ts(struct am65_cpts *cpts,
>   		struct am65_cpts_skb_cb_data *skb_cb =
>   					(struct am65_cpts_skb_cb_data *)skb->cb;
>   
> +		if ((ptp_classify_raw(skb) & PTP_CLASS_V1) &&
> +		    ((mtype_seqid & AM65_CPTS_EVENT_1_SEQUENCE_ID_MASK) ==
> +		     (skb_cb->skb_mtype_seqid & AM65_CPTS_EVENT_1_SEQUENCE_ID_MASK)))
> +			mtype_seqid = skb_cb->skb_mtype_seqid;
> +
>   		if (mtype_seqid == skb_cb->skb_mtype_seqid) {
>   			u64 ns = event->timestamp;
>   
> 
> base-commit: a35e92ef04c07bd473404b9b73d489aea19a60a8

++ Ed Trexel at HP and the Audinate support team for visibility and 
'Tested-by' tags.

Jason Reeder