Re: [PATCH 0/7] PM: Solution for S0ix failure caused by PCH overheating

[Zhang Rui <rui.zhang@intel.com>]

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