On Thu, Nov 21, 2024 at 6:28 PM Antheas Kapenekakis <lkml@xxxxxxxxxxx> wrote: > > The following series moves the _DSM 3,4,7,8 firmware notifications outside > the suspend sequence, and makes them part of a transition function, where > the system can transition freely between them when it is not suspended. > This transition function is exposed to userspace, which now gains the > ability to control the presentation of the device (e.g., pulse the suspend > light) without forcing the kernel to suspend. In addition, it adds support > for the _DSM 9 call Turn Display On, which was introduced in Windows 22H2 > and aims to speed up device wake-up while remaining in the "Sleep" state. > If userspace is not standby aware, the kernel will bring the system into > the "Sleep" state before beginning the suspend sequence. I'll get to this when 6.13-rc1 is out, but I can tell you right away that some of the above cannot be done without breaking backwards compatibility. > This series requires a bit of background on how modern standby works in > Windows. Windows has a concept of "Modern Standby" [1], where it performs > an elaborate userspace and kernel suspend choreography while the device is > inactive in order to maintain fast wake-up times and connectivity while the > display of the device is off. This is done through 5 hardware states and > the OS takes the liberty of transitioning between them, by following a set > of rules (e.g., "Adaptive Hibernate"). > > ``` > \/-> "Hibernate (S4)" > "Active" <-> "Screen Off" <-> "Sleep" <-> "DRIPS" > /\- "Resume" <- <- > ``` > > When the display is on and the user is interacting with the device, it is > in the "Active" state. The moment the display turns off, the device > transitions to the "Screen Off" state, where hardware and userspace are > fully active. Userspace will then decide when appropriate to freeze major > components (such as the DE) and transition into the "Sleep" state, where > the kernel is still active and connectivity is maintained. Finally, the > conventional "Suspend-to-idle" path can be used to bring the system into > the deepest runtime idle platform state (DRIPS) state, which is named > "s2idle" in the Linux kernel. > > After wake-up, the system re-transitions into the "Sleep" state, where > userspace can run housekeeping and/or hibernate if the wake-up was not user > initiated (e.g., timer). If user-initiated, userspace can hasten the > transition out of the "Sleep" state by transitioning into the state > "Resume" that certain devices use to boost the Power Limit (PLx) while > remaining in sleep (support for this new notification is rare). Then, it > transitions back into "Screen Off" and "Active" to prepare for the user. > > All transitions between these states feature unique firmware notifications > [3] that change the presentation of the device (e.g., pulse the suspend > light, turn off RGB). For more information, see the docs in [8]. Making > these transitions accessible from userspace moves them out of the suspend > sequence and has them happen while the kernel is fully active, mirroring > Windows. > > As a side effect, this patch series completely fixes the ROG Ally > controller issue [5], which expects for .5s to lapse before its > controller's USB hub goes into D3 and otherwise malfunctions. It also fixes > an issue present in (allegedly only) older firmwares where they check the > USB subsystem is not in D3 before allowing the controller to wake up while > in powersave mode (for avoiding spurious wake-ups). As such, this patch > series is also a universal fix for the ROG Ally controller. > > Moreover, this patch series allows turning off the controller and RGB of > most Windows handhelds (OneXPlayer, Lenovo Legion Go, GPD, and Asus ROG > Ally), opening the possibility of implementing suspend-then-hibernate and > other standby features, such as background downloads, without waking up the > RGB/controller of those devices. A Thinkpad T14 2021 was also tested, and > it pulses its suspend light during sleep. > > There is still the question of where LSP0 entry/exit (_DSM 5,6) should be > fired or whether they should be fired in the path to hibernation. However, > as they cause no issues currently, and they fire when software activity has > seized, they are fine where they are. > > It is important to note that the effects of these _DSMs persist during > reboots. I.e., if the Legion Go reboots while in the "Sleep" state, it will > boot into the "Sleep" state and have its controller disabled and suspend > light pulsing. The reboot persistence is undesirable, so the reboot path > will need to include a transition to active prior to reboot (not > included in this series). This is not the case after shutdown and > hibernation, where the device boots into the "Active" state. > > The issue of DPMS is still present. Currently, gamescope and KDE (at least) > do not fire DPMS before suspending. This causes an undesirable frozen > screen while the system is suspending and looks quite ugly in general. This > is especially true if the firmware notifications fire earlier. Therefore, > should the kernel fire DPMS before forcing the transition to sleep for > backwards compat.? If yes, it will be quite the effort. Moreover, should > the kernel allow graphics drivers hook the transition function and block > transitions to "Screen Off" if there is an active CRTC? As that would be a > significant undertaking, there should be proof that there exists such a > device that has an issue firing the notifications with an active CRTC. > > A variant of this series has been tested by thousands of users by now, > where the notifications fire around .5s before the CRTC is disabled and no > ill-effects have found in regard to this quirk. AFAIK, it is a visual > quirk. Making DPMS fire before the backwards compat. transition is a good > idea in any case, as it will sync the 200ms between Display Off/Sleep Entry > firing and the graphics driver turning off the display, but it might not be > worth the effort. > > We are currently testing a DPMS patch for gamescope and it completely fixes > this visual quirk while allowing for e.g., hibernation without turning on > the screen. The DPMS gamescope patch + performing the transitions in > userspace in such a way where it blends the Ally's suspend delay halves the > user perceived delay to sleep and results in a very professional > presentation. This presentation extends to other devices as well, such as > the Legion Go. > > Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/prepare-hardware-for-modern-standby [1] > Link: https://learn.microsoft.com/en-us/windows-hardware/customize/power-settings/adaptive-hibernate [2] > Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-firmware-notifications [3] > Link: https://github.com/hhd-dev/hwinfo/tree/master/devices [4] > Link: https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/log/?h=superm1/dsm-screen-on-off [5] > Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2719 [6] > Link: https://dl.dell.com/manuals/all-products/esuprt_solutions_int/esuprt_solutions_int_solutions_resources/client-mobile-solution-resources_white-papers45_en-us.pdf [7] > File: Documentation/admin-guide/pm/standby-states.rst [8] > > Changes from previous series (`acpi/x86: s2idle: move Display off/on calls > outside suspend (fixes ROG Ally suspend)`): > - Separate Display On/Off rename into its own commit (suggested by Hans) > - Move delay quirks into s2idle.c (suggested by Hans) > - Add documentation on Documentation/admin-guide/pm/standby-states.rst > - Callbacks are now static and a transition function is used > - Fixed all checkpatch warnings > - The rest of the series is completely re-written > > Antheas Kapenekakis (13): > Documentation: PM: Add documentation for S0ix Standby States > acpi/x86: s2idle: add support for Display Off and Display On callbacks > acpi/x86: s2idle: add support for Sleep Entry and Sleep Exit callbacks > acpi/x86: s2idle: add support for Turn On Display callback > acpi/x86: s2idle: add modern standby transition function > acpi/x86: s2idle: rename Screen On/Off to Display On/Off > acpi/x86: s2idle: call Display On/Off as part of callbacks > acpi/x86: s2idle: rename MS Exit/Entry to Sleep Exit/Entry > acpi/x86: s2idle: call Sleep Entry/Exit as part of callbacks > acpi/x86: s2idle: add Turn On Display and call as part of callback > acpi/x86: s2idle: add quirk table for modern standby delays > platform/x86: asus-wmi: remove Ally (1st gen) and Ally X suspend quirk > PM: standby: Add sysfs attribute for modern standby transitions > > Documentation/ABI/testing/sysfs-power | 34 +++ > .../admin-guide/pm/standby-states.rst | 133 ++++++++++ > Documentation/admin-guide/pm/system-wide.rst | 1 + > drivers/acpi/x86/s2idle.c | 249 ++++++++++++++---- > drivers/platform/x86/asus-wmi.c | 54 ---- > include/linux/suspend.h | 16 ++ > kernel/power/main.c | 75 ++++++ > kernel/power/power.h | 1 + > kernel/power/suspend.c | 154 +++++++++++ > 9 files changed, 616 insertions(+), 101 deletions(-) > create mode 100644 Documentation/admin-guide/pm/standby-states.rst > > -- > 2.47.0 > >
