hi there, recently I built a small computer with GA-J1900N-D3V motherboard that has soldered down J1900 quad core 2GHz Celeron processor.

More details: <http://bugsplatter.id.au/kernel/boxen/itxmini/>

Problem is that the CPU frequency is displayed 20% high, or 120% of actual value. This is on recent kernels. I posted to the cpufreq mailing list a couple weeks ago with no response.

Today I compiled a 3.10.56 kernel and CPU frequency was correctly displayed, but only 1333MHz and 2000MHz, in one sense closer, but we lost the boost to 2400MHz. The three frequencies of interest are min - 1333MHz, nominal - 2000MHz, max - 2400MHz, these are being wrongly displayed as 1600, 2400 and 2900MHz.

How to fix?

On the webpage above you'll find .configs, dmesg and other info.

Thanks,
Grant.

Are you enabling turbbo and speedstep in the BIOS? What cpufreq profile are you loading in the kernel? What does /proc/cpuinfo show?

Reply from the linux-kernel cpufreq intel-pstate author:
"
intel_pstate enumerates the frequencies by reading MSRs on the
chip. There is a bug in the frequency reporting on Baytrail processors.
Baytrail decided to have the frequency scaled by the bus frequency of
the given SKU instead of a fixed value like the Core processors.

The attached patch should clear this up for you. This patch is going out
today so it should get merged soon. The patch is marked for stable as well.
...
This bug will not affect your performance it is strictly a reporting error.
"
Problem is solved Update the kernel, once the patch makes it upstream.

Grant.