Re: Allowing reset controllers before SMP initialization (on ARM)?

[Maxime Coquelin]

Hi Florian, Arnd,

On 04/16/2015 10:04 AM, Arnd Bergmann wrote:
> On Wednesday 15 April 2015 17:51:18 Florian Fainelli wrote:
> > Hi,
> >
> > In order to support initialization of the secondary core on BCM63138
> > SoCs, I would want to utilize a reset controller to release the
> > secondary CPU from reset [1].
> >
> > Here are multiple options:
> >
> > - expose a custom function which registers the reset controller platform
> > driver as early as possible, which is probably acceptable, but also
> > requires the DT machine descriptor to populate the platform bus earlier,
> > which we could completely avoid
> I think populating the platform bus earlier is not realistic, that
> would break lots of existing dependencies. In particular, we can't
> do it much earlier because it has to be done after the platform bus
> itself is instantiated.
>
> > - have a OF_DECLARE_RESET_CONTROLLER() which is running fairly early
> > during boot, such that we can utilize reset controllers are early as
> > possible,  before any initcall level, and before SMP initialization is
> > kicking in
> We've added a couple of those, and it could be done here, but putting
> them in the right order is a bit tricky, and I think we can avoid it.

I have already proposed a OF_DECLARE_RESET_CONTROLLER() implementation:
https://lkml.org/lkml/2015/2/20/395

I needed it for the STM32 timers, but it was not accepted.
Now, I perform the timers reset in the bootloader, but it shouldn't work 
in your case.

Kind regards,
Maxime
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/