Jérémie Jourdin b0c14eae10 re(4): add hw.re.aspm_disable loader tunable ...

re(4) has unconditionally disabled ASPM L0s/L1 and CLKREQ at attach
for years; on laptops this costs 200mW+ (requested by adrian@ in the PR).

Make it a tunable following the existing hw.re.* pattern:

* default 1 keeps today's behavior;
* 0 preserves the firmware-configured ASPM state at attach and
  skips the watchdog re-assert from the previous revision.

Documented in re.4.

* Verified on RTL8168H (XID 0x541): with hw.re.aspm_disable=0,
  attach no longer logs "ASPM disabled" and pciconf -lcb shows
  the firmware Link Control state preserved -- including Clock PM,
  which the unconditional code previously cleared.

* Default (1) is behaviorally identical to the current driver.

* Note the tunable also stops the driver clearing CLKREQ, a small power
  win even where firmware leaves L0s/L1 off.

Reviewed by:	adrian
Differential Revision:	https://reviews.freebsd.org/D58280
PR: kern/166724

2026-07-19 11:49:14 -07:00

..

if_re.c

re(4): add hw.re.aspm_disable loader tunable

2026-07-19 11:49:14 -07:00