• Rafael J. Wysocki's avatar
    ACPI / PCI / PM: Fix device PM regression related to D3hot/D3cold · 5c7dd710
    Rafael J. Wysocki authored
    Commit 1cc0c998 ("ACPI: Fix D3hot v D3cold confusion") introduced a
    bug in __acpi_bus_set_power() and changed the behavior of
    acpi_pci_set_power_state() in such a way that it generally doesn't work
    as expected if PCI_D3hot is passed to it as the second argument.
    
    First off, if ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) is passed to
    __acpi_bus_set_power() and the explicit_set flag is set for the D3cold
    state, the function will try to execute AML method called "_PS4", which
    doesn't exist.
    
    Fix this by adding a check to ensure that the name of the AML method
    to execute for transitions to ACPI_STATE_D3_COLD is correct in
    __acpi_bus_set_power().  Also make sure that the explicit_set flag
    for ACPI_STATE_D3_COLD will be set if _PS3 is present and modify
    acpi_power_transition() to avoid accessing power resources for
    ACPI_STATE_D3_COLD, because they don't exist.
    
    Second, if PCI_D3hot is passed to acpi_pci_set_power_state() as the
    target state, the function will request a transition to
    ACPI_STATE_D3_HOT instead of ACPI_STATE_D3.  However,
    ACPI_STATE_D3_HOT is now only marked as supported if the _PR3 AML
    method is defined for the given device, which is rare.  This causes
    problems to happen on systems where devices were successfully put
    into ACPI D3 by pci_set_power_state(PCI_D3hot) which doesn't work
    now.  In particular, some unused graphics adapters are not turned
    off as a result.
    
    To fix this issue restore the old behavior of
    acpi_pci_set_power_state(), which is to request a transition to
    ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) if either PCI_D3hot or
    PCI_D3cold is passed to it as the argument.
    
    This approach is not ideal, because generally power should not
    be removed from devices if PCI_D3hot is the target power state,
    but since this behavior is relied on, we have no choice but to
    restore it at the moment and spend more time on designing a
    better solution in the future.
    
    References: https://bugzilla.kernel.org/show_bug.cgi?id=43228Reported-by: default avatarrocko <rockorequin@hotmail.com>
    Reported-by: default avatarCristian Rodríguez <crrodriguez@opensuse.org>
    Reported-and-tested-by: default avatarPeter <lekensteyn@gmail.com>
    Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    5c7dd710
power.c 19.9 KB