[PATCHv2] omap2+: pm: cpufreq: Fix loops_per_jiffy calculation

[Russell King - ARM Linux]

On Fri, Jun 24, 2011 at 11:20:44PM +0530, Premi, Sanjeev wrote:
> I was able to test BogoMIPS calculations via /proc/cpuinfo for
> both with & without CONFIG_SMP selected.
> 
> For most part things work fine - but I do notice occassional Oops
> and segmentation faults while doing "cat /proc/cpuinfo"
> 
> With CONFIG_SMP enabled, system doesn't recover from the Oops;
> but without SMP - I noticed segmentation faults/ BUG but system
> does recover.
> 
> They could be unrelated - but i didn't see any of these earlier
> today. I will continue debug on MON.

I don't think these are related to the patch - I think there's something
up with your hardware.

Let's take the first.

> [root at OMAP3EVM cpufreq]# cat /proc/cpuinfo
> [   73.832366] Internal error: Oops - undefined instruction: 0 [#1] SMP

Ok an undefined instruction.  So...

> [   73.839019] Modules linked in:
> [   73.842193] CPU: 0    Not tainted  (3.0.0-rc3-14002-g40b6752-dirty #21)
> [   73.849121] PC is at __do_fault+0x1c0/0x450
> [   73.853485] LR is at __do_fault+0x2b0/0x450
> [   73.857879] pc : [<c010fa18>]    lr : [<c010fb08>]    psr: 00000113
> [   73.857879] sp : c7907d48  ip : 00000000  fp : c5d518c0
> [   73.869873] r10: 00000200  r9 : 40214000  r8 : 00000000
> [   73.875335] r7 : c2692f98  r6 : c0ad7600  r5 : 87fb018f  r4 : 00000000
> [   73.882141] r3 : 87fb0a3e  r2 : 00000800  r1 : 87fb01cf  r0 : c5d518c0
> [   73.888977] Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
> [   73.896423] Control: 10c5387d  Table: 8795c019  DAC: 00000015
> [   73.902435] Process cat (pid: 449, stack limit = 0xc79062f8)

... lets look at the code line:

> [   74.176879] Code: e1a01005 e3a02000 ebfd1694 e59d0014 (eb07fcba)

and disassemble it:

   0:   e1a01005        mov     r1, r5
   4:   e3a02000        mov     r2, #0  ; 0x0
   8:   ebfd1694        bl      0xfff45a60
   c:   e59d0014        ldr     r0, [sp, #20]
  10:   eb07fcba        bl      0x1ff300

There is no way that 0xeb07fcba should ever cause an undefined ARM
instruction on a properly functioning system.

It points at a hardware problem - are you using a socketed SoC?  Is
it properly socketed?  Is the socket dirty?  And all other questions
related to hardware integrity...