git: pc64 - First hacky attempt at implementing a deep MWAIT sleep inhibitor.

[Imre Vadasz]

commit be6979ca3620cf623ad35c61a21dff68eafa0ebd
Author: Imre Vadász <imre at vdsz.com>
Date:   Fri Jan 23 15:27:44 2026 +0100

    pc64 - First hacky attempt at implementing a deep MWAIT sleep inhibitor.
    
    This is needed by i915(4), to make its DisplayPort code reliable when deep
    MWAIT C-States might be used. Since the i915(4) code is not aware of the
    CPU core that its interrupt is routed to, we have to pessimistically inhibit
    deep MWAIT sleeps on all cores.
    
    This adds a very basic cpu_inhibit_deep_sleep() function to the pc64 platform.
    cpu_inhibit_deep_sleep(1) increments a counter by 1, and
    cpu_inhibit_deep_sleep(0) decrements that counter. And a positive value in
    the counter inhibits deep MWAIT C-States on Intel hardware. Since modern AMD
    hardware uses fully autonomous power-saving state selection, and no MWAIT
    for idling, this function has no effect on AMD right now.

Summary of changes:
 sys/dev/drm/drm/Makefile                       |  1 +
 sys/dev/drm/i915/intel_dp.c                    |  1 +
 sys/dev/drm/include/linux/pm_qos.h             |  5 +++-
 sys/dev/drm/{linux_printf.c => linux_pm_qos.c} | 19 +++++++--------
 sys/platform/pc64/include/cpu.h                |  2 ++
 sys/platform/pc64/x86_64/machdep.c             | 32 +++++++++++++++++++++++++-
 6 files changed, 49 insertions(+), 11 deletions(-)
 copy sys/dev/drm/{linux_printf.c => linux_pm_qos.c} (81%)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/be6979ca3620cf623ad35c61a21dff68eafa0ebd


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