> 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. How do I know if the logic is on or off? Kai-Heng
