[PATCH RFT 1/2] drivers: bus: check cci device tree node status

[Abhilash Kesavan]

Hi Sudeep,

On Wed, Dec 10, 2014 at 9:44 AM, Sudeep Holla <sudeep.holla at arm.com> wrote:
> Hi Abhilash,
>
> On Wednesday 10 December 2014 09:31 AM, Abhilash Kesavan wrote:
>>
>> Hi,
>>
>> On Fri, Nov 28, 2014 at 8:20 PM, Abhilash Kesavan <a.kesavan at samsung.com>
>> wrote:
>>>
>>> The arm-cci driver completes the probe sequence even if the cci node is
>>> marked as disabled. Add a check in the driver to honour the cci status
>>> in the device tree.
>>>
>>> Signed-off-by: Abhilash Kesavan <a.kesavan at samsung.com>
>>
>>
>> This patch helps disable CCI on the Arndale Octa board thus resolving
>> some imprecise aborts seen on that board. Kindly review.
>>
>> Regards,
>> Abhilash
>>>
>>> ---
>>>   drivers/bus/arm-cci.c |    3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
>>> index 860da40..0ce5e2d 100644
>>> --- a/drivers/bus/arm-cci.c
>>> +++ b/drivers/bus/arm-cci.c
>>> @@ -1312,6 +1312,9 @@ static int cci_probe(void)
>>>          if (!np)
>>>                  return -ENODEV;
>>>
>>> +       if (!of_device_is_available(np))
>>> +               return -ENODEV;
>>> +
>
>
> IIUC, by this change you are disabling the MCPM boot protocol here.
> Is there any alternative boot protocol that works on this platform
> to boot all 8 cores ? Sorry by quick grep couldn't find one, hence
> so I am asking.

Thanks for the reply.
On disabling MCPM, we will default to platsmp.c/firmware.c which boots
4 cores as per Kevin's comment here[1]. This was the original behavior
before MCPM was enabled for all 5420 based SoCs.

Regards,
Abhilash
[1] http://www.spinics.net/lists/arm-kernel/msg381191.html
>
> Regards,
> Sudeep
>