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

[John Hupp]

On 6/9/2014 10:20 AM, Seth Forshee wrote:
> On Thu, Jun 05, 2014 at 10:39:46AM -0400, John Hupp wrote:
>> 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
> This command isn't going to work unless you're in a root shell.
>
>> I get the same result using sudo.
> Is it really the same, or does it say "Operation not permitted" instead?
> If so, then it probably means that the driver behind that trip point
> does not support changing the trip point temperature (which isn't
> necessarily a bug, it might really be impossible to change it).

Yes, I verify "Permission  denied":
$ sudo sh -c "echo 75000 > trip_point_1_temp"
sh: 1: cannot create trip_point_1_temp: Permission denied

Since posting, I found this 2007 article that says the kernel no longer 
(as of 2.6.22) supports changing the trip points: 
http://lwn.net/Articles/244595/

Many people reportedly complained about that kernel change, so I wonder, 
is the current kernel design still such that the trip points cannot be 
changed?

Since there are currently no active fan cooling trip points set for this 
Lenovo 3000, only the passive one at 87 C and the critical one at 102 C, 
if I want some active cooling, is my only recourse to modify the DSDT?  
That would seem like a needlessly deep dive, but I'd like to know if 
it's my only option.

>> 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?
>>
>>
>> -- 
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