git: 2c545fcf56db - stable/15 - igc: Check PHY control register reads

The branch stable/15 has been updated by kbowling:

URL: https://cgit.FreeBSD.org/src/commit/?id=2c545fcf56dbacec8597fae9b59b2fc5e3ccb3cd

commit 2c545fcf56dbacec8597fae9b59b2fc5e3ccb3cd
Author:     Kevin Bowling <kbowling@FreeBSD.org>
AuthorDate: 2026-08-11 19:34:29 +0000
Commit:     Kevin Bowling <kbowling@FreeBSD.org>
CommitDate: 2026-08-25 00:29:16 +0000

    igc: Check PHY control register reads
    
    Do not modify a zero-initialized PHY control value when its preceding
    read failed.  Leave the PHY unchanged when the void power helpers cannot
    read its current state.
    
    This follows the defensive checks added to the corresponding e1000
    helpers.
    
    (cherry picked from commit 1121aaa0758baf04bed6f16d4157116b49c25000)
---
 sys/dev/igc/igc_phy.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sys/dev/igc/igc_phy.c b/sys/dev/igc/igc_phy.c
index 13dac1066f27..24ecefb2c625 100644
--- a/sys/dev/igc/igc_phy.c
+++ b/sys/dev/igc/igc_phy.c
@@ -906,10 +906,15 @@ s32 igc_phy_hw_reset_generic(struct igc_hw *hw)
  **/
 void igc_power_up_phy_copper(struct igc_hw *hw)
 {
+	s32 ret_val;
 	u16 mii_reg = 0;
 
 	/* The PHY will retain its settings across a power down/up cycle */
-	hw->phy.ops.read_reg(hw, PHY_CONTROL, &mii_reg);
+	ret_val = hw->phy.ops.read_reg(hw, PHY_CONTROL, &mii_reg);
+	if (ret_val) {
+		DEBUGOUT("Error reading PHY control register\n");
+		return;
+	}
 	mii_reg &= ~MII_CR_POWER_DOWN;
 	hw->phy.ops.write_reg(hw, PHY_CONTROL, mii_reg);
 	usec_delay(300);
@@ -925,10 +930,15 @@ void igc_power_up_phy_copper(struct igc_hw *hw)
  **/
 void igc_power_down_phy_copper(struct igc_hw *hw)
 {
+	s32 ret_val;
 	u16 mii_reg = 0;
 
 	/* The PHY will retain its settings across a power down/up cycle */
-	hw->phy.ops.read_reg(hw, PHY_CONTROL, &mii_reg);
+	ret_val = hw->phy.ops.read_reg(hw, PHY_CONTROL, &mii_reg);
+	if (ret_val) {
+		DEBUGOUT("Error reading PHY control register\n");
+		return;
+	}
 	mii_reg |= MII_CR_POWER_DOWN;
 	hw->phy.ops.write_reg(hw, PHY_CONTROL, mii_reg);
 	msec_delay(1);