linux-kernel - Re: Hard Disk consumes lots of power in s2idle

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Date:   Thu, 20 Feb 2020 16:08:06 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Linux PM <linux-pm@...r.kernel.org>, linux-ide@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>,
        Kent Lin <kent.lin@...onical.com>
Subject: Re: Hard Disk consumes lots of power in s2idle

Hi Srinivas,

> On Feb 20, 2020, at 02:36, Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com> 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.

Kai-Heng

> 
> Thanks,
> Srinivas
> 
> 
>> 
>> Kai-Heng
>