Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <CACRpkdZmax=QpwnfgOJOR-5P3wTyKegaDn=VvhVOYz_AChc7bw@mail.gmail.com>
 <abdc4d16-b2b4-6343-39d6-9bc48e8be43b@gmail.com>
In-Reply-To: <abdc4d16-b2b4-6343-39d6-9bc48e8be43b@gmail.com>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Thu, 3 Mar 2022 23:55:11 +0100
Message-ID: <CACRpkdai4+1NJ+UJxdcEHJjKtccE=LnDyv7pr1pzuQo88-MdaQ@mail.gmail.com>
Subject: Re: Question on expiring HRtimer in-kernel
To:     Matti Vaittinen <mazziesaccount@gmail.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Anna-Maria Gleixner <anna-maria@linutronix.de>,
        Sebastian Reichel <sre@kernel.org>,
        Code Kipper <codekipper@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Linux PM list <linux-pm@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Mar 3, 2022 at 1:43 PM Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> In any case, I remember few cases where I hit nasty issues because I
> used CLOCK_REALTIME - which (AFAIR) is subject to the time adjustments.
> NTP, GPS-time and so on can make the time tick in a strange way :) I
> guess you would have noticed if time was set when timer did expire.
>
> Anyways, I guess the battery charging should rather be tied CLOCK_MONOTONIC.

That makes a lot of sense, and is what I have learned from the internal
kernel primitives as well, I just assumed the HRTimer was some special
kind of beast.

I'll patch this and run some testing, if it goes away with MONOTONIC
I'll send a patch. Thanks!

Yours,
Linus Walleij