From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.deacon@arm.com (Will Deacon)
Date: Thu, 7 May 2015 13:57:53 +0100
Subject: [PATCH v4 0/5] arm64,hi6220: Enable Hisilicon Hi6220 SoC
In-Reply-To: <554B542B.6040006@huawei.com>
References: <1430827599-11560-1-git-send-email-bintian.wang@huawei.com>
 <20150507090210.GB22115@arm.com> <554B305F.4080907@huawei.com>
 <20150507112536.GD22115@arm.com> <554B542B.6040006@huawei.com>
Message-ID: <20150507125752.GE22115@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, May 07, 2015 at 01:01:47PM +0100, Bintian wrote:
> On 2015/5/7 19:25, Will Deacon wrote:
> > On Thu, May 07, 2015 at 10:29:03AM +0100, Bintian wrote:
> >> Hikey is a low cost board, I think it doesn't have an automatic thermal
> >> cut out; I always use HiKey to test my patch, in the normal case,
> >> temperature is not a problem.
> >
> > I don't see why the cost has anything to do with this issue; any money I
> > save on the board will quickly be re-invested in my increased insurance
> > premium.
> >
> > All I think we need is for secure software to keep an eye on the temperature
> > and hit the power controller if it goes over some `fatal' threshold.
> > Ideally, you'd be able to use a secure interrupt for this, but I suspect
> > that you don't have the right hardware features for that (please correct me
> > if I'm wrong). An alternative would be to hang something off a secure timer
> > and get the firmware to check the board temperature on some low-frequency
> > periodic tick.
> If there is exception occurred on A core, there are two methods to
> handle it:
> (1) Delay for a period of time, watchdog will trigger the system reset.
> (2) If the temperature is over 105 degree, the CPU will trigger reset(I
> guess it's chip level).

Aha, so now you're saying that there *is* a hardware shut-off at 105
degrees, regardless of what the kernel is doing? If that's the case, then
we're fine and the current patches make sense in isolation.

Cheers,

Will