[PATCH 2/2] arm64: dts: Add PMU node for APM X-Gene Storm SOC

[Ming Lei]

Hi Jon and Vinayak,

On Tue, Jun 24, 2014 at 11:42 AM, Jon Masters <jcm at redhat.com> wrote:
> On 06/23/2014 10:47 PM, Ming Lei wrote:
>
>> On Thu, Mar 20, 2014 at 5:47 PM, Vinayak Kale <vkale at apm.com> wrote:
>>> This patch adds the PMU device tree node for APM X-Gene Storm SOC.
>>>
>>> Please note that this patch has dependancy on a GIC driver patch [1] which is
>>> yet to be approved by maintainers.
>>>
>>> [1]- https://lkml.org/lkml/2014/2/27/605
>>> (irqchip:gic: change access of gicc_ctrl register to read modify write)
>
>> No matter if Feng Kan's gic patch is applied or not, perf(PMU)
>> still can't work well with your patch, and the failure[1] will be
>> triggered when 'perf top' is started.
>>
>> The failure happened during the 1st pmu overflow interrupt.
>>
>> I test several mustang boards, and all has the problem with
>> upstream kernel.
>
> Note that the GIC bypass register config is set by the firmware and this
> only preserves the original setting, so you could be running an older
> firmware (such as U-Boot). On our (UEFI-enabled systems, complete with
> correct patch) perf top runs correctly without any such problems.

I am wondering if it is related with boot or firmware. We have a board
which is running APM internal 3.12 based kernel, and perf(pmu) works
well. But if I just replace the 3.12 based kernel with upstream kernel
and keep others(boot, kernel parameter, fs, ....) not changed, then
the problem still can happen.

Thanks,
--
Ming Lei