From: Gautham R Shenoy <ego@linux•vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman•id.au>
Cc: "Gautham R. Shenoy" <ego@linux•vnet.ibm.com>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
"Rafael J. Wysocki" <rjw@rjwysocki•net>,
Daniel Lezcano <daniel.lezcano@linaro•org>,
Michael Neuling <mikey@neuling•org>,
Vaidyanathan Srinivasan <svaidy@linux•vnet.ibm.com>,
"Shreyas B. Prabhu" <shreyasbp@gmail•com>,
Shilpasri G Bhat <shilpa.bhat@linux•vnet.ibm.com>,
Stewart Smith <stewart@linux•vnet.ibm.com>,
Balbir Singh <bsingharora@gmail•com>,
"Oliver O'Halloran" <oohall@gmail•com>,
linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
linux-pm@vger•kernel.org, skiboot@lists•ozlabs.org
Subject: Re: [PATCH v3 3/3] powernv: Pass PSSCR value and mask to power9_idle_stop
Date: Tue, 29 Nov 2016 11:40:35 +0530 [thread overview]
Message-ID: <20161129061035.GB30454@in.ibm.com> (raw)
In-Reply-To: <87shqittgx.fsf@concordia.ellerman.id.au>
Hi Michael,
On Wed, Nov 23, 2016 at 08:51:10PM +1100, Michael Ellerman wrote:
> "Gautham R. Shenoy" <ego@linux•vnet.ibm.com> writes:
>
> > From: "Gautham R. Shenoy" <ego@linux•vnet.ibm.com>
> >
> > The power9_idle_stop method currently takes only the requested stop
> > level as a parameter and picks up the rest of the PSSCR bits from a
> > hand-coded macro. This is not a very flexible design, especially when
> > the firmware has the capability to communicate the psscr value and the
> > mask associated with a particular stop state via device tree.
> >
> > This patch modifies the power9_idle_stop API to take as parameters the
> > PSSCR value and the PSSCR mask corresponding to the stop state that
> > needs to be set. These PSSCR value and mask are respectively obtained
> > by parsing the "ibm,cpu-idle-state-psscr" and
> > "ibm,cpu-idle-state-psscr-mask" fields from the device tree.
> >
> > In addition to this, the patch adds support for handling stop states
> > for which ESL and EC bits in the PSSCR are zero. As per the
> > architecture, a wakeup from these stop states resumes execution from
> > the subsequent instruction as opposed to waking up at the System
> > Vector.
> >
> > The older firmware sets only the Requested Level (RL) field in the
> > psscr and psscr-mask exposed in the device tree. For older firmware
> > where psscr-mask=0xf, this patch will set the default sane values that
> > the set for for remaining PSSCR fields (i.e PSLL, MTL, ESL, EC, and
> > TR).
>
> So we're using psscr-mas=0xf as a signal that we're running on old
> firmware.
>
> That's OK I think, but please send a patch to document it in the device
> tree binding.
>
> And call it out below in the code.
Sure will do this! Thanks for reviewing the code.
>
> cheers
>
--
Thanks and Regards
gautham.
next prev parent reply other threads:[~2016-11-29 6:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-10 7:54 [PATCH v3 0/3] powernv:stop: Use psscr_val,mask provided by firmware Gautham R. Shenoy
2016-11-10 7:54 ` [PATCH v3 1/3] powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro Gautham R. Shenoy
2016-11-29 10:42 ` Balbir Singh
2016-11-10 7:54 ` [PATCH v3 2/3] cpuidle:powernv: Add helper function to populate powernv idle states Gautham R. Shenoy
2016-11-23 9:49 ` Michael Ellerman
2016-11-29 6:09 ` Gautham R Shenoy
2016-11-10 7:54 ` [PATCH v3 3/3] powernv: Pass PSSCR value and mask to power9_idle_stop Gautham R. Shenoy
2016-11-23 9:51 ` Michael Ellerman
2016-11-29 6:10 ` Gautham R Shenoy [this message]
2016-11-29 6:34 ` [PATCH v3 0/3] powernv:stop: Use psscr_val,mask provided by firmware Balbir Singh
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