Bug 60201

Summary: [Patch] Add support for enabling Intel Atom N2000 series C-states
Product: Power Management Reporter: ianp (snailbox88-dev)
Component: intel_idleAssignee: Len Brown (lenb)
Status: CLOSED INVALID    
Severity: enhancement CC: aaron.lu
Priority: P1 Keywords: trivial
Hardware: All   
OS: Linux   
Kernel Version: 3.9.7 Subsystem:
Regression: No Bisected commit-id:
Attachments: Patch to support model 54 Atoms (N2600/N2800) in intel_idle

Description ianp 2013-06-27 09:27:46 UTC 
$ cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 54
model name	: Intel(R) Atom(TM) CPU N2800   @ 1.86GHz
stepping	: 1
microcode	: 0x10c
cpu MHz		: 798.000
cache size	: 512 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 2
apicid		: 0
initial apicid	: 0
fdiv_bug	: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 10
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm arat dtherm
bogomips	: 3724.21
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 32 bits virtual
power management:

As per Intel's datasheet on Atom Processor D2000 and N2000 series [1], this processor supports C-states:
  Support CPU states: C0 and C1 (for D2000 series); C0-C4, C1E-C4E, Deep Power
  Down Technology (code named C6)(for N2000 series)

But intel_idle reports otherwise:
$ dmesg | grep idle
[    2.087387] intel_idle: does not run on family 6 model 54
[    2.104933] cpuidle: using governor ladder
[    2.104982] cpuidle: using governor menu

I'm attaching a patch that adds support in intel_idle for model 54 Atoms (N2600/N2800).

[1] https://www-ssl.intel.com/content/www/us/en/processors/atom/atom-d2000-n2000-vol-1-datasheet.html
Comment 1 ianp 2013-06-27 09:29:57 UTC 
Created attachment 106131 [details]
Patch to support model 54 Atoms (N2600/N2800) in intel_idle
Comment 2 Aaron Lu 2013-07-09 08:09:24 UTC 
Please submit patches to linux-pm mailing list for merge, bugzilla is not meant to serve this purpose, thanks.
Comment 3 ianp 2013-07-10 10:16:04 UTC 
Yes, sorry about that.

I overlooked the documentation that came with the Linux kernel codebase regarding submitting patches.