ice: fall back to TCXO on TSPLL lock fail

JIRA: https://issues.redhat.com/browse/RHEL-104246

Upstream commit(s):
commit 84b8694
Author: Karol Kolacinski <karol.kolacinski@intel.com>
Date:   Mon Jun 23 17:30:02 2025 -0700

    ice: fall back to TCXO on TSPLL lock fail

    TSPLL can fail when trying to lock to TIME_REF as a clock source, e.g.
    when the external clock source is not stable or connected to the board.
    To continue operation after failure, try to lock again to internal TCXO
    and inform user about this.

    Reviewed-by: Milena Olech <milena.olech@intel.com>
    Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
    Tested-by: Rinitha S <sx.rinitha@intel.com>
    Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Signed-off-by: Petr Oros <poros@redhat.com>

Author: orosp

drivers/net/ethernet/intel/ice/ice_tspll.c

@@ -605,5 +605,17 @@ int ice_tspll_init(struct ice_hw *hw)
 	/* Configure the TSPLL using the parameters from the function
 	 * capabilities.
 	 */
-	return ice_tspll_cfg(hw, tspll_freq, clk_src);
+	err = ice_tspll_cfg(hw, tspll_freq, clk_src);
+	if (err) {
+		dev_warn(ice_hw_to_dev(hw), "Failed to lock TSPLL to predefined frequency. Retrying with fallback frequency.\n");
+
+		/* Try to lock to internal TCXO as a fallback. */
+		tspll_freq = ice_tspll_default_freq(hw->mac_type);
+		clk_src = ICE_CLK_SRC_TCXO;
+		err = ice_tspll_cfg(hw, tspll_freq, clk_src);
+		if (err)
+			dev_warn(ice_hw_to_dev(hw), "Failed to lock TSPLL to fallback frequency.\n");
+	}
+
+	return err;
 }