git: 6000eb72a5ba - stable/15 - e1000: Disable autonomous PCH power gating after reset

The branch stable/15 has been updated by kbowling:

URL: https://cgit.FreeBSD.org/src/commit/?id=6000eb72a5ba44069bf5290a3504db892cb6dfdb

commit 6000eb72a5ba44069bf5290a3504db892cb6dfdb
Author:     Kevin Bowling <[email protected]>
AuthorDate: 2026-08-11 15:23:51 +0000
Commit:     Kevin Bowling <[email protected]>
CommitDate: 2026-08-18 01:29:43 +0000

    e1000: Disable autonomous PCH power gating after reset
    
    Panther Point changed the reset value of CTRL_EXT.DPG_EN to enable
    autonomous power gating. Clear it after hardware reset on Panther Point
    and Nova Point controllers to prevent unexpected Tx/Rx hangs, packet
    loss, or corruption.
    
    (cherry picked from commit 0979b0430c2d728e595841ecba30b63972794fe9)
---
 sys/dev/e1000/e1000_defines.h | 1 +
 sys/dev/e1000/e1000_ich8lan.c | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/sys/dev/e1000/e1000_defines.h b/sys/dev/e1000/e1000_defines.h
index f1b1008764a1..9b8aca173856 100644
--- a/sys/dev/e1000/e1000_defines.h
+++ b/sys/dev/e1000/e1000_defines.h
@@ -66,6 +66,7 @@
 
 /* Extended Device Control */
 #define E1000_CTRL_EXT_LPCD		0x00000004 /* LCD Power Cycle Done */
+#define E1000_CTRL_EXT_DPG_EN		0x00000008 /* Dynamic Power Gating */
 #define E1000_CTRL_EXT_SDP4_DATA	0x00000010 /* SW Definable Pin 4 data */
 #define E1000_CTRL_EXT_SDP6_DATA	0x00000040 /* SW Definable Pin 6 data */
 #define E1000_CTRL_EXT_SDP3_DATA	0x00000080 /* SW Definable Pin 3 data */
diff --git a/sys/dev/e1000/e1000_ich8lan.c b/sys/dev/e1000/e1000_ich8lan.c
index 3102505faa15..f1a5fe59bb81 100644
--- a/sys/dev/e1000/e1000_ich8lan.c
+++ b/sys/dev/e1000/e1000_ich8lan.c
@@ -5094,6 +5094,14 @@ static s32 e1000_reset_hw_ich8lan(struct e1000_hw *hw)
 	reg |= E1000_KABGTXD_BGSQLBIAS;
 	E1000_WRITE_REG(hw, E1000_KABGTXD, reg);
 
+	/* Prevent autonomous power gating after the hardware reset. */
+	if (hw->mac.type >= e1000_pch_ptp &&
+	    hw->mac.type < e1000_82575) {
+		reg = E1000_READ_REG(hw, E1000_CTRL_EXT);
+		reg &= ~E1000_CTRL_EXT_DPG_EN;
+		E1000_WRITE_REG(hw, E1000_CTRL_EXT, reg);
+	}
+
 	return E1000_SUCCESS;
 }