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 for <linuxppc-dev@lists.ozlabs.org>; Thu, 13 Apr 2017 14:12:23 +1000 (AEST)
Message-ID: <1492056725.7236.95.camel@kernel.crashing.org>
Subject: Re: [PATCH 3/3] powernv:idle: Set LPCR_UPRT on wakeup from deep-stop
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, "Gautham R.
 Shenoy" <ego@linux.vnet.ibm.com>, Michael Ellerman <mpe@ellerman.id.au>,
 Michael Neuling <mikey@neuling.org>, "Shreyas B. Prabhu"
 <shreyasbp@gmail.com>, Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>,
 Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>, Anton Blanchard
 <anton@samba.org>, Balbir Singh <bsingharora@gmail.com>, Akshay Adiga
 <akshay.adiga@linux.vnet.ibm.com>, Nicholas Piggin <npiggin@gmail.com>,
 Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Date: Thu, 13 Apr 2017 14:12:05 +1000
In-Reply-To: <8737ddq7py.fsf@skywalker.in.ibm.com>
References: <cover.1491996797.git.ego@linux.vnet.ibm.com>
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On Thu, 2017-04-13 at 09:28 +0530, Aneesh Kumar K.V wrote:
> >   #endif
> >        mtctr   r12
> >        bctrl
> > +/*
> > + * cur_cpu_spec->cpu_restore would restore LPCR to a
> > + * sane value that is set at early boot time,
> > + * thereby clearing LPCR_UPRT.
> > + * LPCR_UPRT is required if we are running in Radix mode.
> > + * Set it here if that be the case.
> > + */
> > +BEGIN_MMU_FTR_SECTION
> > +     mfspr   r3, SPRN_LPCR
> > +     LOAD_REG_IMMEDIATE(r4, LPCR_UPRT)
> > +     or      r3, r3, r4
> > +     mtspr   SPRN_LPCR, r3
> > +END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)

We are probably better off saving the value somewhere during boot
and just "blasting" it whole back.

Cheers
Ben.