[OLPC-AU] lid close while shutting down

James Cameron quozl at laptop.org
Tue Feb 14 06:09:22 EST 2012

The XO-1.5 does not overheat if used properly.

The XO-1.5 has higher CPU performance than an XO-1, and also generates
more heat than an XO-1.

The heat is transfered through a heat spreader to the upper casing.  The
total heat generated is limited by the battery capacity.  If the
temperature exceeds a set point, the processor is stopped, and further
heat generation is significantly reduced.  This is under control of the
hardware, not the software.

However, it is easy for incorrect impressions about the design to
spread, based on ad-hoc analysis and reporting.

For example, because of an episode of damage that happened when a stack
of laptops was left on and their lid sensors interacted, and because of
the use of early prototypes with an incomplete heat spreader, no doubt a
myth has developed that the thermal design of the laptop is bad.

However, the software has been enhanced to fix the lid sensor
interaction, and the heat spreaders of early prototypes can be tested
and fixed.  Moreover, our tests in ovens showed that the thermal design
can be trusted.

What's the context of your questions?  Please give more detail.

I've tested; if the lid is closed after the shutdown option is selected
in Sugar, the lid close suspend is avoided, the screen shows the
shutdown UL warnings, and within the normal time for a shutdown (i.e.
depending on the speed of the internal microSD), it turns off the power.

In addition, opening the lid does not cancel the shutdown, nor does
opening and closing the lid rapidly.

These tests were with build 883, OLPC OS 11.3.0 on XO-1.5.  You should
test with your own builds, especially if you make any alterations to the
powerd configuration or the kernel.

You can verify from power logs whether the users have properly shutdown
their laptops.  Please ensure this logging works well, as it will give
you good data.  Obtain the logs whenever there is a report of laptop
thermal issues.  Require that the logging is implemented as part of any
remedial action.

There is certainly possibility for damage if the laptop is placed in an
insulated bag or stacked with other laptops without being shutdown.
There is also possibility of damage to other items in an insulated bag.

Physically shutting the lid ... alone ... may increase the temperature
of the laptop, but not to a great extent, and only if the software does
not shutdown.  The increase is from the reduced cooling available; the
front face is insulated by the keyboard, and the back face is no longer
vertical.  As a result of not being vertical, the airflow is reduced,
which reduces the transfer of heat to the air.

I don't think a powered-on XO gets very hot at all if the lid is shut.
It merely grows slightly warmer.

On Tue, Feb 14, 2012 at 09:04:40PM +1100, Sridhar Dhanapalan wrote:
> What happens if the XO's lid is closed after the shutdown option is
> selected in Sugar?
> Is there a chance that the XO does not shut down - e.g. suspends or
> gets stuck in some limbo state?
> Is there a possibility for them to get damaged? I'd think that a
> powered-on XO would get very hot if the lid was shut.
> Sridhar
> Sridhar Dhanapalan
> Engineering Manager
> One Laptop per Child Australia
> M: +61 425 239 701
> E: sridhar at laptop.org.au
> A: G.P.O. Box 731
> ?? ? Sydney, NSW 2001
> W: www.laptop.org.au
> _______________________________________________
> OLPC-AU mailing list
> OLPC-AU at lists.laptop.org
> http://lists.laptop.org/listinfo/olpc-au

James Cameron

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