Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <0f39c2be651d75895d3dfca1d8afc7cad2d4a1af.camel@intel.com>
Subject: Re: [PATCH 0/7] PM: Solution for S0ix failure caused by PCH
 overheating
From:   Zhang Rui <rui.zhang@intel.com>
To:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Oliver Neukum <oneukum@suse.com>
Cc:     "Rafael J. Wysocki" <rjw@rjwysocki.net>, kvalo@kernel.org,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Linux PM <linux-pm@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        linux-rtc@vger.kernel.org,
        "open list:NETWORKING DRIVERS (WIRELESS)" 
        <linux-wireless@vger.kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        merez@codeaurora.org, mat.jonczyk@o2.pl,
        Sumeet Pawnikar <sumeet.r.pawnikar@intel.com>,
        Len Brown <len.brown@intel.com>
Date:   Thu, 05 May 2022 23:18:02 +0800
In-Reply-To: <CAJZ5v0hceDVkv05=SFbO53wsmHWkrs1SSoxZ=FuErYsnNutGWg@mail.gmail.com>
References: <20220505015814.3727692-1-rui.zhang@intel.com>
         <40b8ad06-6ef2-113c-fffb-2fa001603b3f@suse.com>
         <CAJZ5v0hceDVkv05=SFbO53wsmHWkrs1SSoxZ=FuErYsnNutGWg@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi, Neukum,

Thanks for your response, I missed your original reply in my Inbox.

On Thu, 2022-05-05 at 14:02 +0200, Rafael J. Wysocki wrote:
> On Thu, May 5, 2022 at 10:23 AM Oliver Neukum <oneukum@suse.com>
> wrote:
> > 
> > 
> > 
> > On 05.05.22 03:58, Zhang Rui wrote:
> > > On some Intel client platforms like SKL/KBL/CNL/CML, there is a
> > > PCH thermal sensor that monitors the PCH temperature and blocks
> > > the system
> > > from entering S0ix in case it overheats.
> > > 
> > > Commit ef63b043ac86 ("thermal: intel: pch: fix S0ix failure due
> > > to PCH
> > > temperature above threshold") introduces a delay loop to cool the
> > > temperature down for this purpose.
> > > 
> > > However, in practice, we found that the time it takes to cool the
> > > PCH down
> > > below threshold highly depends on the initial PCH temperature
> > > when the
> > > delay starts, as well as the ambient temperature.
> > > 
> > > This patch series has been tested on the same Dell XPS 9360
> > > laptop and
> > > S0ix is 100% achieved across 1000+ s2idle iterations.
> > > 
> > 
> > Hi,
> > 
> > what is the user experience if this ever triggers? At that stage
> > the
> > system will appear to be suspended to an external observer, won't
> > it?
> > So in effect you'd have a system that spontaneously wakes up, won't
> > you?
> 
> No, you won't.
> 
> It will just go ahead and reach S0ix when it can.  It will only wake
> up if there's a legitimate wakeup even in the meantime.

Please correct me if I misunderstand your question, Oliver.

Without the patch, the system becomes suspended and stays in PCx.
With the patch, the system first stays in PCx during suspending (in the
intel_pch_thermal driver' cooling delays), and then becomes suspended
and stays in S0ix.

thanks,
rui