Hi, This is an attempt at a solution to perform activities necessary while entering deeper low power modes supported by firmware for QCOM SoCs which have hardened IP (Resource Power Manager Hardened - RPMH) for shared resource management. The shared resources that are no longer used, when processor enters deep idle states, can be turned off or put to lower state via sleep requests. Clients vote for lower resource state when application processor is asleep. These votes need to be flushed only during entry to low power modes. In addition to this, an always-on power domain wake-up timer present in PDC (Power Domain Controller) needs to be programmed so that RSC is up and running by the time CPU has to wake-up. The kernel does not notify that the CPU powering down is the last CPU. Therefore, in this series, we are doing a reference count to determine the last CPU in the system to enter idle and use that to perform the last-man activities. It would be optimal to do this than to flush whenever a core enters idle. The current approach can be revisited in future if OS-initiated support becomes available that enables certain actions to be taken when last core enters deepest low power mode. Apart from idle sleep, the deeper low modes can be exercised in system suspend. As it is expected that all other cores except the core entering system suspend will be disabled during suspend operations, the device suspend calls are utilized to perform the required tasks. Please review these patches. Your inputs would be greatly appreciated. Thanks, Raju Dependencies: The current series depends on patches[1][2], which add RPMH communication support, to send shared resource request votes by clients. The patches[1][2] also provide functions that are expected to be called by sleep manager client during low power mode entry. The other patches[3][4][5] which fix couple of issues are also needed. Apart from RPMH related patches, the current series depends on knowing the next wake up timer of a CPU[6] for programing the always-on timer present in PDC. [1]. https://lkml.org/lkml/2018/6/20/519 [2]. https://lkml.org/lkml/2018/7/27/326 [3]. https://lkml.org/lkml/2018/7/13/358 [4]. https://lkml.org/lkml/2018/7/19/84 [5]. https://lkml.org/lkml/2018/8/24/641 [6]. https://lkml.org/lkml/2018/6/20/800 Raju P.L.S.S.S.N (6): drivers: qcom: system_pm: add system PM client for RPMH based SoCs dt-bindings: introduce System PM bindings for Qualcomm SoCs drivers: qcom: system_pm: Add power management ops drivers: qcom: system_pm: program next wakeup to PDC timer drivers: qcom: rpmh: force flush new sleep/wake requests during suspend drivers: soc: system_pm: Add suspend notifier .../devicetree/bindings/soc/qcom/system_pm.txt | 28 ++++ drivers/soc/qcom/Kconfig | 11 ++ drivers/soc/qcom/Makefile | 1 + drivers/soc/qcom/rpmh-internal.h | 1 + drivers/soc/qcom/rpmh.c | 17 +++ drivers/soc/qcom/system_pm.c | 168 +++++++++++++++++++++ include/soc/qcom/rpmh.h | 5 + 7 files changed, 231 insertions(+) create mode 100644 Documentation/devicetree/bindings/soc/qcom/system_pm.txt create mode 100644 drivers/soc/qcom/system_pm.c -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation.
