oprofile and ARM A9 hardware counter

[Shilimkar, Santosh]

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.

Regards
Santosh