[PATCH v1] thermal: imx: Update critical temp threshold

[Francesco Dolcini]

Hello Daniel, Sasha, Shawn and all

On Mon, May 09, 2022 at 11:55:20AM +0200, Daniel Lezcano wrote:
> On 20/04/2022 11:13, Francesco Dolcini wrote:
> > Increase the critical temperature threshold to the datasheet defined
> > value according to the temperature grade of the SoC, increasing the
> > actual critical temperature value of 5 degrees.
> > 
> > Without this change the emergency shutdown will trigger earlier then
> > required affecting applications that are expected to be working on this
> > close to the limit, but yet valid, temperature range.
> > 
> > Signed-off-by: Francesco Dolcini <francesco.dolcini at toradex.com>
> > ---
> > 
> > Not sure if there is an alternative to this patch, the critical threshold seems
> > to be read-only and it is not possible to just change it from user space that
> > would be my preferred solution.
> > 
> > According to the original discussion [1] the reasoning was the following:
> > 
> > On Tue, Jul 28, 2015 at 4:50 PM, Tim Harvey <tharvey at gateworks.com> wrote:
> > > Yes - the purpose of lowering the critical threshold from the hardware
> > > default is to allow Linux to shutdown more cleanly.
> > 
> > But I do not understand it.
> 
> Shawn, Sascha ? any comment ?

Just one small addition, we (Toradex) are using this modified critical
threshold since quite some time, on multiple i.MX[67]* SOC, and we
regularly run stress tests on commercial/IT part on the whole
temperature working range (ambient temperature up to 85 degrees for IT
modules) in climate chambers and I'm not aware of any issue reported
because of that (indeed, it is the other way around, without this change
we had issues).

Francesco