[PATCH] e1000e: set fixed clock frequency indication for Alder Point

[Rawda, Tony]

On some Alder Point (e1000_pch_adp) platforms the XTAL value reported in
the software STRAP is incorrect, so the SYSCFI bit in TSYNCRXCTL selects
a 24 MHz base frequency while the SYSTIM counter actually advances at
38.4 MHz. As a result the PTP hardware clock runs ~1.6x too fast
(38.4/24), which prevents ptp4l and other PTP-based time sync from
disciplining the clock.

Commit 688a0d61b2d7 ("e1000e: set fixed clock frequency indication for
Nahum 11 and Nahum 13") fixed the same problem for e1000_pch_mtp,
e1000_pch_lnp and e1000_pch_ptp. Alder Point silicon likewise always
runs at 38.4 MHz, so give it the same fixed-frequency override in both
e1000e_get_base_timinca() and e1000e_ptp_init().

Observed on an HP Z2 Mini G9 with I219-LM (17) [8086:1a1c]: before the
change the PHC advanced 16.0 s per 10.0 s of wall-clock time and
/sys/class/ptp/ptpN/max_adjustment read 999999999 (MAX_PPB_24MHZ);
afterwards it advances ~10.0 s and max_adjustment reads 230769100
(MAX_PPB_38400KHZ).

Fixes: 59e466888038 ("e1000e: Add support for Alder Lake")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tony Rawda <Tony.Rawda@xxxxxxxxxx>
---
 drivers/net/ethernet/intel/e1000e/netdev.c | 2 +-
 drivers/net/ethernet/intel/e1000e/ptp.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 844f31ab37ad..635a18cfc93f 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -3543,7 +3543,6 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca)
 		break;
 	case e1000_pch_cnp:
 	case e1000_pch_tgp:
-	case e1000_pch_adp:
 	case e1000_pch_nvp:
 		if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI) {
 			/* Stable 24MHz frequency */
@@ -3559,6 +3558,7 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca)
 			adapter->cc.shift = shift;
 		}
 		break;
+	case e1000_pch_adp:
 	case e1000_pch_mtp:
 	case e1000_pch_lnp:
 	case e1000_pch_ptp:
diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index ec39e35f3857..4955d29e47f7 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -291,13 +291,13 @@ void e1000e_ptp_init(struct e1000_adapter *adapter)
 		break;
 	case e1000_pch_cnp:
 	case e1000_pch_tgp:
-	case e1000_pch_adp:
 	case e1000_pch_nvp:
 		if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI)
 			adapter->ptp_clock_info.max_adj = MAX_PPB_24MHZ;
 		else
 			adapter->ptp_clock_info.max_adj = MAX_PPB_38400KHZ;
 		break;
+	case e1000_pch_adp:
 	case e1000_pch_mtp:
 	case e1000_pch_lnp:
 	case e1000_pch_ptp:
-- 
2.53.0