[RFC PATCH 1/2] core: implement OPAL_SIGNAL_SYSTEM_RESET with POWER9 scoms

[Nicholas Piggin]

On Wed, 13 Sep 2017 09:18:34 +1000
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:

> On Wed, 2017-09-13 at 02:05 +1000, Nicholas Piggin wrote:
> > This implements a way to raise system reset interrupts on other
> > cores. This has not yet been tested on DD2 or with deeper sleep
> > states.  
> 
> Reminds me, we need to workaround a bug with XSCOMs on P9
> 
> PSCOMs to core in the range 20010A80-20010Ab8 (list below) can fail
> occasionally with an error of 4 (PCB_ADDRESS_ERROR). We need to
> (silently) retry up to 32 times.

[snip]

So, just put a loop into xscom_read and xscom_write for those
addresses for P9 chips?

Thanks,
Nick