Re: Bug#763320: linux-image-3.16-2-amd64: intel_idle enabled for Intel Atom S1260, causes high CPU temperature when idle

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2014-09-30 02:13, Ben Hutchings wrote:
> On Mon, 2014-09-29 at 11:57 +0200, Christophe Thil wrote:
>> Package: src:linux
>> Version: 3.16.3-2
>> Severity: normal
>>
>> Dear Maintainer,
>>
>> with Kernel 3.16, intel_idle is enabled for the Intel Atom S1260 CPU
>> (Centerton SoC). This leads to a +20°C temperature increase when the CPU
>> is idle, exceeding the 100°C alarm threshold for passive cooled systems
>> like the Supermicro X9SBAA-F.
>>
>> With 3.14, intel_idle was blacklisted for this CPU, which runs fine. If
>> 3.16 is booted with intel_idle.max_cstate=0 processor.max_cstate=0,
>> which disables the intel_idle, the CPU also stays cool.
> [...]
> 
> It looks like the relevant change is:
> 
> commit acead1b0fac5b10d0ae3f1cc5f7820b9f9f924f5
> Author: Jan Kiszka <jan.kiszka@siemens.com>
> Date:   Sat Jan 25 22:24:22 2014 +0100
> 
>     intel_idle: Add CPU model 54 (Atom N2000 series)
>     
>     Add CPU ID for Atom N2600/N2800 processors. Datasheets indicate support
>     for this, detailed information about potential quirks or limitations are
>     missing, though. So we just reuse the definition for the previous ATOM
>     series. [...]
> 
> as those processors are part of the same Atom generation as Centerton.
> 
> I think that more specific ID matching is required here.

Hmm, I would check first if the Centerton series really has the same
model ID (0x36) as the Cedarview. If they do, what other means of
differentiation do we have?

Jan

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