linux-kernel - Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

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Date:   Wed, 23 Nov 2016 10:35:16 +1100
From:   Michael Neuling <mikey@...ling.org>
To:     Michael Ellerman <mpe@...erman.id.au>,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

On Wed, 2016-11-23 at 10:30 +1100, Michael Ellerman wrote:
> "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com> writes:
> 
> > From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
> > 
> > Ensure that PSSCR is set to a safe value corresponding to no
> > state-loss each time a POWER9 CPU comes online.
> 
> Is this a bug fix? I can't tell from the change log.

There are no known bugs it's fixing.  

It's just safer to run with a known default value, rather than what we randomly
inherit from previous firmware.

Mikey