linux_dsm_epyc7002/kernel/power
Rafael J. Wysocki ac9eafbe93 ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices
According to Section 3.5 of the "Intel Low Power S0 Idle" document [1],
Function 5 of the LPS0 _DSM is expected to be invoked when the system
configuration matches the criteria for entering the target low-power
state of the platform.  In particular, this means that all devices
should be suspended and in low-power states already when that function
is invoked.

This is not the case currently, however, because Function 5 of the
LPS0 _DSM is invoked by it before the "noirq" phase of device suspend,
which means that some devices may not have been put into low-power
states yet at that point.  That is a consequence of the previous
design of the suspend-to-idle flow that allowed the "noirq" phase of
device suspend and the "noirq" phase of device resume to be carried
out for multiple times while "suspended" (if any spurious wakeup
events were detected) and the point of the LPS0 _DSM Function 5
invocation was chosen so as to call it (and LPS0 _DSM Function 6
analogously) once per suspend-resume cycle (regardless of how many
times the "noirq" phases of device suspend and resume were carried
out while "suspended").

Now that the suspend-to-idle flow has been redesigned to carry out
the "noirq" phases of device suspend and resume once in each cycle,
the code can be reordered to follow the specification that it is
based on more closely.

For this purpose, add ->prepare_late and ->restore_early platform
callbacks for suspend-to-idle, to be executed, respectively, after
the "noirq" phase of suspending devices and before the "noirq"
phase of resuming them and make ACPI use them for the invocation
of LPS0 _DSM functions as appropriate.

While at it, move the LPS0 entry requirements check to be made
before invoking Functions 3 and 5 of the LPS0 _DSM (also once
per cycle) as follows from the specification [1].

Link: https://uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf # [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
2019-08-08 11:26:01 +02:00
..
autosleep.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
console.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
energy_model.c sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity() 2019-06-24 19:23:39 +02:00
hibernate.c SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
Kconfig pci-v5.3-changes 2019-07-15 20:44:49 -07:00
main.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
Makefile PM: Introduce an Energy Model management framework 2018-12-11 15:16:58 +01:00
power.h PM: hibernate: powerpc: Expose pfn_is_nosave() prototype 2019-06-14 10:48:56 +02:00
poweroff.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 248 2019-06-19 17:09:08 +02:00
process.c PM / sleep: Show freezing tasks that caused a suspend abort 2018-09-10 12:09:10 +02:00
qos.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
snapshot.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
suspend_test.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
suspend.c ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices 2019-08-08 11:26:01 +02:00
swap.c kernel: power: swap: use kzalloc() instead of kmalloc() followed by memset() 2019-06-28 10:20:39 +02:00
user.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
wakelock.c PM / wakeup: Only update last time for active wakeup sources 2018-05-10 11:39:19 +02:00