On Thu, May 07, 2015 at 01:01:47PM +0100, Bintian wrote:

On 2015/5/7 19:25, Will Deacon wrote:

quoted

On Thu, May 07, 2015 at 10:29:03AM +0100, Bintian wrote:

quoted

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