[PATCH iwl-net] ice: fix PTP timestamping broken by SyncE code on E825C

[Petr Oros <poros@redhat.com>]

The E825C SyncE support added in commit ad1df4f2d591 ("ice: dpll:
Support E825-C SyncE and dynamic pin discovery") introduced a SyncE
reconfiguration block in ice_ptp_link_change() that prevents
ice_ptp_port_phy_restart() from being called in several error paths.
Without the PHY restart, PTP timestamps stop working after any link
change event.

There are three ways the PHY restart gets blocked:

1. When DPLL initialization fails (e.g. missing ACPI firmware node
   properties), ICE_FLAG_DPLL is not set and the function returns early
   before reaching the PHY restart.

2. When ice_tspll_bypass_mux_active_e825c() fails to read the CGU
   register, WARN_ON_ONCE fires and the function returns early.

3. When ice_tspll_cfg_synce_ethdiv_e825c() fails to configure the
   clock divider for an active pin, same early return.

SyncE and PTP are independent features. SyncE reconfiguration failures
must not prevent the PTP PHY restart that is essential for timestamp
recovery after link changes.

Fix by making the entire SyncE block conditional on ICE_FLAG_DPLL
without an early return, and replacing the WARN_ON_ONCE + return error
handling inside the loop with dev_err_once + break. The function always
proceeds to ice_ptp_port_phy_restart() regardless of SyncE errors.

Fixes: ad1df4f2d591 ("ice: dpll: Support E825-C SyncE and dynamic pin discovery")
Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice_ptp.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
index 094e96219f4565..60bc47099432a2 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -1296,12 +1296,10 @@ void ice_ptp_link_change(struct ice_pf *pf, bool linkup)
 	if (pf->hw.reset_ongoing)
 		return;
 
-	if (hw->mac_type == ICE_MAC_GENERIC_3K_E825) {
+	if (hw->mac_type == ICE_MAC_GENERIC_3K_E825 &&
+	    test_bit(ICE_FLAG_DPLL, pf->flags)) {
 		int pin, err;
 
-		if (!test_bit(ICE_FLAG_DPLL, pf->flags))
-			return;
-
 		mutex_lock(&pf->dplls.lock);
 		for (pin = 0; pin < ICE_SYNCE_CLK_NUM; pin++) {
 			enum ice_synce_clk clk_pin;
@@ -1314,15 +1312,19 @@ void ice_ptp_link_change(struct ice_pf *pf, bool linkup)
 								port_num,
 								&active,
 								clk_pin);
-			if (WARN_ON_ONCE(err)) {
-				mutex_unlock(&pf->dplls.lock);
-				return;
+			if (err) {
+				dev_err_once(ice_pf_to_dev(pf),
+					     "Failed to read SyncE bypass mux for pin %d, err %d\n",
+					     pin, err);
+				break;
 			}
 
 			err = ice_tspll_cfg_synce_ethdiv_e825c(hw, clk_pin);
-			if (active && WARN_ON_ONCE(err)) {
-				mutex_unlock(&pf->dplls.lock);
-				return;
+			if (active && err) {
+				dev_err_once(ice_pf_to_dev(pf),
+					     "Failed to configure SyncE ETH divider for pin %d, err %d\n",
+					     pin, err);
+				break;
 			}
 		}
 		mutex_unlock(&pf->dplls.lock);
-- 
2.52.0