From mboxrd@z Thu Jan  1 00:00:00 1970
From: Leo Yan <leo.yan@linaro.org>
Subject: Re: [PATCH v2 1/5] thermal: change "hysteresis" as optional property
Date: Tue, 8 Mar 2016 21:57:43 +0800
Message-ID: <20160308135743.GC4921@leoy-linaro>
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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
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Hi Eduardo,

On Fri, Mar 04, 2016 at 11:57:53AM +0000, Javi Merino wrote:
> On Fri, Mar 04, 2016 at 11:03:49AM +0800, Leo Yan wrote:
> > On Thu, Mar 03, 2016 at 08:29:44AM -0800, Eduardo Valentin wrote:
> > > On Fri, Feb 26, 2016 at 11:43:43AM +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.

Thanks,
Leo Yan