On Tuesday, March 11, 2014 01:08:13 PM Dirk Brandewie wrote: > On 03/11/2014 12:50 PM, Rafael J. Wysocki wrote: > > On Tuesday, March 11, 2014 10:58:59 AM Dirk Brandewie wrote: > >> Hi Patrick, > >> > >> Sorry for the slow response you caught me taking a few days off :-) > >> > >> On 03/07/2014 07:49 AM, Patrik Lundquist wrote: > >>> Hi, > >>> > >>> booting 3.13.5 on a dual socket Ivy Bridge-EP resulted in this error: > >>> > >>> [ 0.194139] smpboot: CPU0: Intel(R) Xeon(R) CPU E5-2687W v2 @ > >>> 3.40GHz (fam: 06, model: 3e, stepping: 04) > >>> ... > >>> [ 0.246755] x86: Booting SMP configuration: > >>> [ 0.250935] .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 > >>> [ 0.357648] .... node #1, CPUs: #8 #9 #10 #11 #12 #13 #14 #15 > >>> [ 0.553293] x86: Booted up 2 nodes, 16 CPUs > >>> [ 0.557666] smpboot: Total of 16 processors activated (108850.19 BogoMIPS) > >>> ... > >>> [ 5.210204] Intel P-state driver initializing. > >>> [ 5.232407] Intel pstate controlling: cpu 0 > >>> [ 5.253628] Intel pstate controlling: cpu 1 > >>> [ 5.274899] cpufreq: __cpufreq_add_dev: ->get() failed > >>> [ 5.294856] Intel pstate controlling: cpu 2 > >>> [ 5.313553] Intel pstate controlling: cpu 3 > >>> [ 5.332526] Intel pstate controlling: cpu 4 > >>> [ 5.352347] Intel pstate controlling: cpu 5 > >>> [ 5.372112] Intel pstate controlling: cpu 6 > >>> [ 5.391097] Intel pstate controlling: cpu 7 > >>> [ 5.410272] Intel pstate controlling: cpu 8 > >>> [ 5.429092] Intel pstate controlling: cpu 9 > >>> [ 5.447714] Intel pstate controlling: cpu 10 > >>> [ 5.465872] Intel pstate controlling: cpu 11 > >>> [ 5.482942] Intel pstate controlling: cpu 12 > >>> [ 5.498414] Intel pstate controlling: cpu 13 > >>> [ 5.513586] Intel pstate controlling: cpu 14 > >>> [ 5.529200] Intel pstate controlling: cpu 15 > >>> > >>> CPU 1 is alive and well but missing the cpufreq driver. The system is > >>> running fine otherwise. > >> > >> This is a regression introduced by commit > >> da60ce9f2fa cpufreq: call cpufreq_driver->get() after calling ->init() > >> > >> > >> A return of zero from cpufreq_driver->get() is a warning at best for > >> intel_pstate at init time. In fact zero is a valid return value AFAICT. > > > > Well, is it? So what is the 0 supposed to mean? > > Zero frequency the core is not running. I said it is a valid answer not that I > should be returning it. There is nothing in the docs or headers that I can > find that says Zero is a failure value. > > In this case the the error should be a warning maybe __cpufreq_add_dev() the > only use of policy->cur is the bootloader workaround. There's another check in cpufreq_update_policy() that also fails if 0 is returned from ->get(). Definitely, 0 is not the right answer to the "What frequency is the CPU running at?" question. It doesn't have a defined meaning either. Rafael -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
