On 06/20/2017 09:54 AM, Sudeep Holla wrote: > > > On 20/06/17 17:20, Florian Fainelli wrote: >> On 06/20/2017 02:10 AM, Lorenzo Pieralisi wrote: >>> [+Sudeep] >>> >>> On Mon, Jun 19, 2017 at 10:32:38AM -0700, Florian Fainelli wrote: >>>> On 06/19/2017 05:24 AM, Mark Rutland wrote: >>>>> On Fri, Jun 16, 2017 at 05:07:40PM -0700, Florian Fainelli wrote: >>>>>> Hi all, >>>>> >>>>> Hi Florian, >>>>> >>>>>> This patch series makes ARM's fncpy() implementation more generic (dropping the >>>>>> Thumb-specifics) and available in an asm-generic header file. >>>>>> >>>>>> Tested on a Broadcom ARM64 STB platform with code that is written to SRAM. >>>>>> >>>>>> Changes in v3 (thanks Doug!): >>>>>> - correct include guard names in asm-generic/fncpy.h to __ASM_FNCPY_H >>>>>> - utilize Kbuild to provide the fncpy.h header on ARM64 >>>>>> >>>>>> Changes in v2: >>>>>> - leave the ARM implementation where it is >>>>>> - make the generic truly generic (no) >>>>>> >>>>>> This is helpful in making SoC-specific power management code become true drivers >>>>>> that can be shared between different architectures. >>>>>> Could you elaborate on what this is needed for? >>>> >>>> Several uses cases come to mind: >>>> >>>> - it could be used as a trampoline code prior to entering S2 for systems >>>> that do not support PSCI 1.0 >>> >>> I think S2 here means PM_SUSPEND_MEM. It is very wrong to manage power >>> states through platform specific hooks on PSCI based systems, consider >>> upgrading to PSCI 1.0 please (or implement PSCI CPU_SUSPEND power >>> states that allow to achieve same power savings as PM_SUSPEND_MEM >>> by just entering suspend-to-idle). >> >> S2 is PM_SUSPEND_STANDBY and S3 is PM_SUSPEND_MEM, at least that how I >> read it. I would rather we update to PSCI 1.0 (at least) to properly >> support SYSTEM_SUSPEND rather than retrofitting a system-wide suspend >> state into CPU_SUSPEND since that seems wrong. >> > > This has been discussed multiple times in the past. No one has come back > with strong reason to add that to the PSCI SYSTEM_SUSPEND API. > > Care to explain the difference between PM_SUSPEND_STANDBY and S3 is > PM_SUSPEND_MEM on your platform. And why it can't be achieved with > suspend-to-idle ? S2 preserves the ON/OFF island power and allows wake logic to wake the system (infrared, GPIOs, Wake-on-LAN/WLAN, etc.) whereas S3 allows powering off the ON/OFF island entirely, and allows for a lower power consumption, with a subset of the wake peripherals to actually wake the system. S5 is also implemented although its use case is narrower (soft-off). The higher latency involved in S3 entry/exit is totally accepted due to the higher power savings that it yields. > > You can always report any issue with PSCI specification at > errata@xxxxxxx as mentioned in the document. I just did because there are a few other things missing. -- Florian
