Bureaucrats, dave_user, Administrators
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DAVE Embedded Systems' team is available for any additional information, please contact [mailto:sales@dave.eu sales@dave.eu].
Suggested part are ATS Push Pin Heat Sinks CPX0250250xx or FPX0250250xx part numbers. See ATS website for more details [https://www.qats.com/eShop.aspx?productGroup=0&subGroup=3&q=Push%20Pin]. ===Software thermal protection ''TBD: se applicabile'' ===
In DESK-MX8-L, two software thermal protection mechanisms are implemented. Both are based on the processor's temperature sensor. It is worth remembering that maximum junction temperature (also denoted as Tj in the rest of the document) is:
*95°C for commercial Consumer parts*105°C for extended commercial and industrial Industrial parts*125°C for automotive parts{| style="color:#000000; border:solid 2px #73B2C7; background-color:#ededed;font-size:95%; vertical-align:middle;"| [[File:TBD.png|30px]]| '''Section not completed yet'''|}
====U-Boot====
At U-Boot level, automatic boot procedure is halted until Tj is smaller than (following temperatures might seem excessively low but they take into account the intrinsic poor precision of the temperature sensor to provide a reasonable safe margin):
*80°C TBD for commercial Consumer parts*90 95°C for extended commercial and industrial Industrial parts*110°C for automotive parts.
====Linux kernel====
The default temperature thresholds depend on the silicon grade, as follows:
*for commercial Consumer parts** passive threshold: '''TBD'''** critical threshold: '''TBD'''*for Industrial parts
** passive threshold: 85°C
** critical threshold: 90°C*for extended commercial and industrial parts** passive threshold: 95°C** critical threshold: 100°C*for automotive parts** passive threshold: 115°C** critical threshold: 120°C.
Practically speaking, for DESK-MX8-L this mechanism makes use of two different thresholds, denoted as <code>trip_point0</code> (also known as ''passive threshold'') and <code>trip_point1</code> (also known as ''critical threshold)''.
When Tj reaches <code>trip_point0</code>, Linux kernel scales down processor frequency: <pre>System is too hot. GPU3D will work at 1/64 clock.</pre>
If Tj reaches <code>trip_point1</code>, a complete shutdown is triggered:
<pre>
thermal thermal_zone0: critical temperature reached(100 95 C),shutting down
</pre>
By default, temperature thresholds are set up as follows:
*<code>trip_point0</code>: 85°C
*<code>trip_point1</code>: 100°C95°C.
Trip point thresholds can be accessed via <code>sysfs</code> interface from user space. The following example shows how to read the values of the trip points:
<pre>
root@axel-litemito:~# cat /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_temp
85000
root@axel-litemito:~# cat /sys/devices/virtual/thermal/thermal_zone0/trip_point_1_temp100000950000
</pre>
This example shows how to set trip points 0 and 1 to 95°C and 100°C respectively:
echo 100000 > /sys/class/thermal/thermal_zone0/trip_point_1_temp
</pre>
To read current processor temperature please issue this command (reported temperature is 36.676°C in the example):
<pre>
root@axel-litemito:~# cat /sys/class/thermal/thermal_zone0/temp
36676
</pre>