echo 75000 > /sys/class/thermal/thermal_zone0/trip_point_1_temp - Permission denied!!

[John Hupp]

Trying to edit an acpi thermal trip point, I show from 
/sys/class/thermal/thermal_zone0:

$ echo 75000 > trip_point_1_temp
bash: trip_point_1_temp: Permission denied

I get the same result using sudo.

I also tried with the same result:

$ echo 75000 | sudo tee trip_point_1_temp
and
$ sudo sh -c "echo 75000 > trip_point_1_temp"

I also tried "echo -n" instead of just "echo" with the same result.

I also tried echo "75000" instead of just echo 75000.

I also tried the above commands from 
/sys/devices/virtual/thermal/thermal_zone0 (where the links from 
/sys/class/thermal point), all with the same result.

These thermal attributes are supposed to be editable by the user, and 
this is confirmed by 
https://www.kernel.org/doc/Documentation/thermal/x86_pkg_temperature_thermal

I have read that there was one or more bugs in the past that behaved 
this way.  Do we have a new bug?