Date: Sun, 20 Mar 2016 23:40:31 +0800
From: Leo Yan <leo.yan@linaro.org>
To: Javi Merino <javi.merino@arm.com>
Cc: Eduardo Valentin <edubezval@gmail.com>, Wei Xu <xuwei5@hisilicon.com>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>, Zhang Rui <rui.zhang@intel.com>,
        kongxinwei <kong.kongxinwei@hisilicon.com>,
        Punit Agrawal <Punit.Agrawal@arm.com>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 1/5] thermal: change "hysteresis" as optional property
Message-ID: <20160320154031.GA12693@leoy-linaro>
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Hi Javi,

Sorry for late response.

On Wed, Mar 09, 2016 at 11:10:52AM +0000, Javi Merino wrote:
> On Tue, Mar 08, 2016 at 12:55:59PM -0800, Eduardo Valentin wrote:
> > On Tue, Mar 08, 2016 at 09:57:43PM +0800, Leo Yan wrote:

[...]

> > > > > > > The property "hysteresis" is mandatory for trip points, so if without
> > > > > > > it the thermal zone cannot register successfully. But "hysteresis" is
> > > > > > > ignored in the thermal subsystem and only inquired by several thermal
> > > > > > > sensor drivers.
> > > > > > 
> > > > > > If the Linux thermal subsystem has a problem with handling hysteresis, I
> > > > > > would rather fix Linux code than relaxing the DT binding. Or if you
> > > > > > still believe hysteresis is really optional, I would prefer to see a
> > > > > > better justification than "Linux ignores it".
> > > > 
> > > > I see it the other way round, Is hysteresis a property that, without
> > > > it, the thermal code can't configure itself so it fails to create the
> > > > trip point?  The current code goes "There is no hysteresis for this
> > > > property, I don't know how to set up this trip point!".  I think we
> > > > can do better than this.
> > > 
> > > Do you agree with Javi's suggestion? If you think it's okay, I will
> > > move on to send out a new version patch based on Javi's comments.
> > 
> > No I don't. This discussion so far has been about Linux code. I still
> > havent seen an argument explaining why hysteresis has to be optional.
> 
> Fair enough.  Looks like I'm holding this driver from being
> upstreamed, so I'll back off.
> 
> Leo, sorry for misguiding you.  Please bring back the hysteresis
> property you had in v1.

Not at all. I will add back hysteresis property and resend new patches.

Thanks,
Leo Yan