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Date:   Mon, 4 Nov 2019 10:45:23 -0500
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     Tom Cook <tom.k.cook@gmail.com>
Cc:     linux-kernel@vger.kernel.org
Subject: Re: Power management - HP 15-ds0502na
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On Mon, Nov 04, 2019 at 10:06:48AM -0500, Theodore Y. Ts'o wrote:
> Actually, it's probably because one of the device drives isn't
> properly putting that particular device into a low power state.  When
> I was trying to make s2idle work on the XPS 13, there was needed patch
> to make the SATA AHCI controller go into a lower power state.  This
> was a patch which the Dell folks had gotten into their special
> "Optimized for Dell laptops" Ubuntu kernel that was running into
> resistance upstream.  I *think* that patch finally made it upstream,
> but to be honest, I haven't been keeping track since I decided "life
> was too short to fight and make s2idle work".

Oh, and I forgot; the other thing I had to do to get s2idle's power
consumption down to suspend-2-ram was to unload the SD card reader;
apparently that device driver didn't know how to do the low power
saving thing under OS control.  So I ultimately was able to get the
power while suspended of s2idle down to that of s2ram.  What I wasn't
able to solve for my laptop was the reliability of resuming after the
suspend....

						- Ted