linux-kernel - Power management

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Message-ID: <CAFSh4UxSx7SYT=Ja6TbwFwCJm_yn6VtMapXGv3B=+g2rQcALSA@mail.gmail.com>
Date:   Mon, 4 Nov 2019 11:21:24 +0000
From:   Tom Cook <tom.k.cook@...il.com>
To:     linux-kernel@...r.kernel.org
Subject: Power management - HP 15-ds0502na

Hi all,

I've recently purchased an HP 2-in-1 laptop, model 15-ds0502na.  This
is a Ryzen 7 3700U processor.  There seems to be some difficulty
between HP's firmware ACPI tables and the kernel.  It's not clear (to
me, at least) whether this is poor ACPI implementation from HP or poor
handling of valid ACPI tables by the kernel.  The most obvious
symptoms are:

* Pre-5.3 kernels don't boot at all.  This appears to be because the
FADT table declares the hardware_reduced flag and this was not very
well supported.  5.3 kernels boot okay (I'm using the one that comes
with Ubuntu 15.10).
* Power management doesn't work very well.  The most obvious symptom
of this is that /sys/power/mem_sleep contains only "[s2idle]" and so
there is no suspend-to-RAM available.  Setting
"mem_sleep_default=deep" on the command line doesn't change this.
* There are a few devices that appear to be on I2C buses and declared
in the ACPI tables (eg the fingerprint sensor) which don't show up
under Linux.  They did under Windows, until I blew the Windows
installation away to install Linux, and I'm assuming that Windows
found them through the ACPI DSDT.  Now thinking it may have been handy
to keep Windows around for debugging, but that's regrets for you.

Is this the right place to raise this?  If there's some other place
that Linux ACPI issues are dealt with, please point me there as I've
not had any luck googling.

What are my next steps debugging this?  I've decompiled the firmware
ACPi tables but I don't have much idea what I'm looking at.

Thanks,
Tom Cook