> On Feb 20, 2020, at 18:34, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > > On Thu, Feb 20, 2020 at 11:25 AM Kai-Heng Feng > <kai.heng.feng@xxxxxxxxxxxxx> wrote: >> >> >> >>> On Feb 20, 2020, at 18:12, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: >>> >>> On Thu, Feb 20, 2020 at 9:08 AM Kai-Heng Feng >>> <kai.heng.feng@xxxxxxxxxxxxx> wrote: >>>> >>>> Hi Srinivas, >>>> >>>>> On Feb 20, 2020, at 02:36, Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote: >>>>> >>>>> Hi Kai, >>>>> >>>>> On Wed, 2020-02-19 at 22:22 +0800, Kai-Heng Feng wrote: >>>>>> Hi Srinivas, >>>>>> >>>>>> Your previous work to support DEVSLP works well on SATA SSDs, so I am >>>>>> asking you the issue I am facing: >>>>>> Once a laptop has a HDD installed, the power consumption during >>>>>> S2Idle increases ~0.4W, which is quite a lot. >>>>>> However, HDDs don't seem to support DEVSLP, so I wonder if you know >>>>>> to do proper power management for HDDs? >>>>> What is the default here >>>>> cat /sys/power/mem_sleep >>>>> s2idle or deep? >>>> >>>> It defaults to s2idle. >>>> >>>>> >>>>> Please follow debug steps here: >>>>> https://01.org/blogs/qwang59/2018/how-achieve-s0ix-states-linux >>>>> >>>>> We need to check whether you get any PC10 residency or not. >>>> >>>> Yes it reaches PC10. It doesn't reach SLP_S0 though. >>>> The real number on S2Idle power consumption: >>>> No HDD: ~1.4W >>>> One HDD: ~1.8W >>>> >>>> If the SoC doesn't hit PC10 the number should be significantly higher. >>>> That's why I think the issue is the power management on HDD itself. >>> >>> I'm assuming that you mean a non-SSD device here. >> >> Yes, it's spinning rust here. >> >>> >>> That would be handled via ata_port_suspend() I gather and whatever >>> that does should do the right thing. >>> >>> Do you think that the disk doesn't spin down or it spins down, but the >>> logic stays on? >> >> The spin sound is audible, so I am certain the HDD spins down during S2Idle. > > OK > >> How do I know if the logic is on or off? > > Well, if it were off, it would not draw power. :-) > > So IMO it is reasonable to assume that the logic on the drive stays > on. I'm not aware of anything that can be done to turn it off, > however. Okay, thanks for the info. I'll ask vendors the possibility to handle it at system firmware level. Kai-Heng
