net: ethernet: ti: cpsw: disable PTPv1 hw timestamping advertisement

The TI CPTS does not natively support PTPv1, only PTPv2. But, as it
happens, the CPTS can provide HW timestamp for PTPv1 Sync messages, because
CPTS HW parser looks for PTP messageType id in PTP message octet 0 which
value is 0 for PTPv1. As result, CPTS HW can detect Sync messages for PTPv1
and PTPv2 (Sync messageType = 0 for both), but it fails for any other PTPv1
messages (Delay_req/resp) and will return PTP messageType id 0 for them.

The commit e9523a5 ("net: ethernet: ti: cpsw: enable
HWTSTAMP_FILTER_PTP_V1_L4_EVENT filter") added PTPv1 hw timestamping
advertisement by mistake, only to make Linux Kernel "timestamping" utility
work, and this causes issues with only PTPv1 compatible HW/SW - Sync HW
timestamped, but Delay_req/resp are not.

Hence, fix it disabling PTPv1 hw timestamping advertisement, so only PTPv1
compatible HW/SW can properly roll back to SW timestamping.

Fixes: e9523a5 ("net: ethernet: ti: cpsw: enable HWTSTAMP_FILTER_PTP_V1_L4_EVENT filter")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20201029190910.30789-1-grygorii.strashko@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/cpsw_ethtool.c

@@ -728,7 +728,6 @@ int cpsw_get_ts_info(struct net_device *ndev, struct ethtool_ts_info *info)
 		(1 << HWTSTAMP_TX_ON);
 	info->rx_filters =
 		(1 << HWTSTAMP_FILTER_NONE) |
-		(1 << HWTSTAMP_FILTER_PTP_V1_L4_EVENT) |
 		(1 << HWTSTAMP_FILTER_PTP_V2_EVENT);
 	return 0;
 }

drivers/net/ethernet/ti/cpsw_priv.c

@@ -639,13 +639,10 @@ static int cpsw_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
 		break;
 	case HWTSTAMP_FILTER_ALL:
 	case HWTSTAMP_FILTER_NTP_ALL:
-		return -ERANGE;
 	case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
 	case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
 	case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
-		priv->rx_ts_enabled = HWTSTAMP_FILTER_PTP_V1_L4_EVENT;
-		cfg.rx_filter = HWTSTAMP_FILTER_PTP_V1_L4_EVENT;
-		break;
+		return -ERANGE;
 	case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
 	case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
 	case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ: