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.
