linux-kernel - Re: [PATCH v2 6/6] platform/x86: ayaneo-ec: Add suspend hook

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Message-ID: 
 <CAGwozwFDsn0xm_mG4ypEym=K8c81qqi=qtJL=06nP6SzdFaFoQ@mail.gmail.com>
Date: Tue, 28 Oct 2025 22:39:52 +0100
From: Antheas Kapenekakis <lkml@...heas.dev>
To: Mario Limonciello <superm1@...nel.org>
Cc: platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hwmon@...r.kernel.org, Hans de Goede <hansg@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Derek John Clark <derekjohn.clark@...il.com>,
	Joaquín Ignacio Aramendía <samsagax@...il.com>,
	Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH v2 6/6] platform/x86: ayaneo-ec: Add suspend hook

On Tue, 28 Oct 2025 at 22:21, Mario Limonciello <superm1@...nel.org> wrote:
>
> On 10/28/25 3:34 PM, Antheas Kapenekakis wrote:
> >>> The fan speed is also lost during hibernation, but since hibernation
> >>> failures are common with this class of devices
> Why are hibernation failures more common in this class of device than
> anything else?  The hibernation flow is nearly all done in Linux driver
> code (with the exception of ACPI calls that move devices into D3 and out
> of D0).

I should correct myself here and say hibernation in general in Linux
leaves something to be desired.

Until secure boot supports hibernation, that will be the case because
not enough people use it.

I have had it break for multiple reasons, not incl. the ones below and
the ones we discussed last year where games are loaded.

For a few months I fixed some of the bugs but it is not sustainable.

> Perhaps you're seeing a manifestation of a general issue that we're
> working on a solution for here:
>
> https://lore.kernel.org/linux-pm/20251025050812.421905-1-safinaskar@gmail.com/
>
> https://lore.kernel.org/linux-pm/20251026033115.436448-1-superm1@kernel.org/
>
> https://lore.kernel.org/linux-pm/5935682.DvuYhMxLoT@rafael.j.wysocki/T/#u
>
> Or if you're on an older kernel and using hybrid sleep we had a generic
> issue there as well which was fixed in 6.18-rc1.
>
> Nonetheless; don't make policy decisions based upon kernel bugs.  Fix
> the kernel bugs.

My problem is I cannot in good conscience restore a fan speed before
the program responsible for it is guaranteed to thaw.

The best solution I can come up with would be in freeze save if manual
control is enabled, disable it, and then on resume set a flag that
makes the first write to fan speed also set pwm to manual.

This way suspend->hibernate flows, even if hibernation hangs when
creating the image, at least have proper fan control because they are
unattended, and resume hangs work similarly.

Antheas