netdev - [PATCH net 3/3] e1000e: set fixed clock frequency indication for Nahum 11 and Nahum 13

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Message-ID: <20250617172444.1419560-4-anthony.l.nguyen@intel.com>
Date: Tue, 17 Jun 2025 10:24:43 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	andrew+netdev@...n.ch,
	netdev@...r.kernel.org
Cc: Vitaly Lifshits <vitaly.lifshits@...el.com>,
	anthony.l.nguyen@...el.com,
	dima.ruinskiy@...el.com,
	richardcochran@...il.com,
	Mor Bar-Gabay <morx.bar.gabay@...el.com>,
	Gil Fine <gil.fine@...ux.intel.com>
Subject: [PATCH net 3/3] e1000e: set fixed clock frequency indication for Nahum 11 and Nahum 13

From: Vitaly Lifshits <vitaly.lifshits@...el.com>

On some systems with Nahum 11 and Nahum 13 the value of the XTAL clock in
the software STRAP is incorrect. This causes the PTP timer to run at the
wrong rate and can lead to synchronization issues.

The STRAP value is configured by the system firmware, and a firmware
update is not always possible. Since the XTAL clock on these systems
always runs at 38.4MHz, the driver may ignore the STRAP and just set
the correct value.

Fixes: cc23f4f0b6b9 ("e1000e: Add support for Meteor Lake")
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@...el.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@...el.com>
Reviewed-by: Gil Fine <gil.fine@...ux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/e1000e/netdev.c | 14 +++++++++++---
 drivers/net/ethernet/intel/e1000e/ptp.c    |  8 +++++---
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index a96f4cfa6e17..7719e15813ee 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -3534,9 +3534,6 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca)
 	case e1000_pch_cnp:
 	case e1000_pch_tgp:
 	case e1000_pch_adp:
-	case e1000_pch_mtp:
-	case e1000_pch_lnp:
-	case e1000_pch_ptp:
 	case e1000_pch_nvp:
 		if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI) {
 			/* Stable 24MHz frequency */
@@ -3552,6 +3549,17 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca)
 			adapter->cc.shift = shift;
 		}
 		break;
+	case e1000_pch_mtp:
+	case e1000_pch_lnp:
+	case e1000_pch_ptp:
+		/* System firmware can misreport this value, so set it to a
+		 * stable 38400KHz frequency.
+		 */
+		incperiod = INCPERIOD_38400KHZ;
+		incvalue = INCVALUE_38400KHZ;
+		shift = INCVALUE_SHIFT_38400KHZ;
+		adapter->cc.shift = shift;
+		break;
 	case e1000_82574:
 	case e1000_82583:
 		/* Stable 25MHz frequency */
diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index 89d57dd911dc..ea3c3eb2ef20 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -295,15 +295,17 @@ void e1000e_ptp_init(struct e1000_adapter *adapter)
 	case e1000_pch_cnp:
 	case e1000_pch_tgp:
 	case e1000_pch_adp:
-	case e1000_pch_mtp:
-	case e1000_pch_lnp:
-	case e1000_pch_ptp:
 	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_mtp:
+	case e1000_pch_lnp:
+	case e1000_pch_ptp:
+		adapter->ptp_clock_info.max_adj = MAX_PPB_38400KHZ;
+		break;
 	case e1000_82574:
 	case e1000_82583:
 		adapter->ptp_clock_info.max_adj = MAX_PPB_25MHZ;
-- 
2.47.1