oprofile and ARM A9 hardware counter

[Shilimkar, Santosh]

On Wed, Jan 18, 2012 at 1:24 PM, Ming Lei <ming.lei at canonical.com> wrote:
> On Wed, Jan 18, 2012 at 7:39 PM, Shilimkar, Santosh
> <santosh.shilimkar at ti.com> wrote:
>> On Wed, Jan 18, 2012 at 10:33 AM, Ming Lei <ming.lei at canonical.com> wrote:
>>> Hi Will and stephane,
>>>
>>> On Wed, Jan 18, 2012 at 12:18 PM, Ming Lei <ming.lei at canonical.com> wrote:
>>>> Hi stephane & Will,
>>>>
>>>> On Tue, Jan 10, 2012 at 8:46 AM, stephane eranian
>>>> <eranian at googlemail.com> wrote:
>>>>> See the dmesg from my 3.2 kernel:
>>>>>
>>>>>
>>>>> [    0.000000] Booting Linux on physical CPU 0[    0.000000]
>>>
>>> But if you test omap4 perf against -next kernel, pmu won't work because
>>> the commit[1] may put 'emu_sys_clkdm'  clock domain into HW_AUTO mode,
>>> so writing pmu register may not take effect.
>>>
>>> I have found  the similar problem on cam clock domain before[2].
>>> CD_EMU is very simliar with CD_CAM in the point below:
>>>
>>>        CD_EMU has no static or module wake-up dependency with any other clock
>>>        domain of the device.[3]
>>>
>>> So the patch[4] can make omap4 pmu work on -next tree.
>>>
>>> Shilimkar, care to comment on the patch[4]?
>>>
>>> thanks,
>>> --
>>> Ming Lei
>>>
>>> [1], commit 3c50729b3fa1cd8ca1f347e6caf1081204cf1a7c
>>> Author: Santosh Shilimkar <santosh.shilimkar at ti.com>
>>> Date:   Wed Jan 5 22:03:17 2011 +0530
>>>
>>>   ARM: OMAP4: PM: Initialise all the clockdomains to supported states
>>>
>>>   Initialise hardware supervised mode for all clockdomains if it's
>>>   supported. Initiate sleep transition for other clockdomains,
>>>   if they are not being used.
>>>
>>> [2], http://www.spinics.net/lists/linux-omap/msg61911.html
>>>
>>> [3], 3.6.12.3 of OMAP4 TRM
>>>
>>> [4],
>>> diff --git a/arch/arm/mach-omap2/clockdomains44xx_data.c
>>> b/arch/arm/mach-omap2/clockdomains44xx_data.c
>>> index 9299ac2..41d2260 100644
>>> --- a/arch/arm/mach-omap2/clockdomains44xx_data.c
>>> +++ b/arch/arm/mach-omap2/clockdomains44xx_data.c
>>> @@ -390,7 +390,7 @@ static struct clockdomain emu_sys_44xx_clkdm = {
>>>        .prcm_partition   = OMAP4430_PRM_PARTITION,
>>>        .cm_inst          = OMAP4430_PRM_EMU_CM_INST,
>>>        .clkdm_offs       = OMAP4430_PRM_EMU_CM_EMU_CDOFFS,
>>> -       .flags            = CLKDM_CAN_HWSUP,
>>> +       .flags            = CLKDM_CAN_SWSUP,
>>>  };
>> NAK.
>>
>> You don't need this patch. What you saw on CAMERA was indeed
>> a known bug but emulation domain has no such issues.
>>
>> So the accesses to emulation register should continue to work
>> with the clock-domain being kept under hardware supervision.
>
> But why can this patch make omap4 pmu work?  Without the patch,
> there are no CTI interrupts generated for pmu irq.
>
Interesting. For me debugger works which also relies on Emulation domain.

Need to see why CTI is behaving like this.

Regards
Santosh