Re: [PATCH 2/3] arm64: dts: r8a7795: Add Cortex-A57 CPU cores

[Magnus Damm <magnus.damm@gmail.com>]

Hi Dirk,

On Tue, Dec 15, 2015 at 5:48 PM, Dirk Behme <dirk.behme@gmail.com> wrote:
> On 15.12.2015 09:38, Magnus Damm wrote:
>>
>> Hi Simon,
>>
>> On Sat, Dec 12, 2015 at 8:07 AM, Simon Horman <horms@verge.net.au> wrote:
>>>
>>> On Fri, Dec 04, 2015 at 02:38:52PM +0100, Dirk Behme wrote:
>>>>
>>>> From: Gaku Inami <gaku.inami.xw@bp.renesas.com>
>>>>
>>>> Add Cortex-A57 CPU cores to r8a7795 SoC for a total of 4 x Cortex-A57.
>>>>
>>>> Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
>>>> Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
>>>> Sigend-off-by: Dirk Behme <dirk.behme@gmail.com>
>>>
>>>
>>> Thanks, I have queued this up for v4.5.
>>
>>
>> Thanks. May I ask if CPU hotplug is known to work?
>
>
>
> I didn't test that.

Ok, no worries. I feel that there are various CPU related features
that need a bit of testing to make sure support is stable enough to
enable without causing issues for other on-going development.

CPU Hotplug is one of those, another is kernel command line options
like maxcpus, and kexec would be good to have working as well. To make
things a bit more complicated, there is a rather complicated software
stack with trusted code installed by the boot loader, so there is a
dependency on that as well. On earlier SoCs from previous generations
there were issues with shared reset vectors and a watchdog, so SMP
support may affect watchdog too...

>> Also, which version
>> of the boot loader stack is required?
>
> I've the U-Boot / boot loader stack from BSP v3.0.2 on the board. I haven't
> tested v3.0.3, yet.

Thanks for sharing!

Cheers,

/ magnus