From: Michael Ellerman <mpe@ellerman•id.au>
To: "Gautham R. Shenoy" <ego@linux•vnet.ibm.com>,
Stewart Smith <stewart@linux•vnet.ibm.com>,
skiboot@lists•ozlabs.org <skiboot@lists•ozlabs.org>
Cc: 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>,
Balbir Singh <bsingharora@gmail•com>,
Shilpasri G Bhat <shilpa.bhat@linux•vnet.ibm.com>,
linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
linux-pm@vger•kernel.org,
"Gautham R. Shenoy" <ego@linux•vnet.ibm.com>
Subject: Re: [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop
Date: Tue, 04 Oct 2016 21:32:23 +1100 [thread overview]
Message-ID: <87int84d6w.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <21e080ffa52f432b40750028a624aee1baebbaf7.1475130107.git.ego@linux.vnet.ibm.com>
"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.
That looks good.
> This patch depends on the following skiboot patch that exports the
> PSSCR values and the mask for all the stop states:
> https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html
But we can't depend on a skiboot patch. The kernel has to cope with
running on an old skiboot.
I realise this is for Power9, and we haven't shipped any of them yet.
But skiboot has had Power9 support since May, so I don't think we want
to declare that all of those skiboot versions are unsupported because of
this.
So is there any way we can make this work on skiboot versions that don't
have the patch above?
cheers
next prev parent reply other threads:[~2016-10-04 10:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-29 7:05 [PATCH 0/2] powernv:stop: Use psscr_val,mask provided by firmware Gautham R. Shenoy
2016-09-29 7:05 ` [PATCH 1/2] powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro Gautham R. Shenoy
2016-09-29 7:05 ` [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop Gautham R. Shenoy
2016-10-04 10:32 ` Michael Ellerman [this message]
2016-10-04 11:33 ` Balbir Singh
2016-10-07 7:20 ` Gautham R Shenoy
2016-10-12 5:35 ` Stewart Smith
2016-10-13 11:23 ` Gautham R Shenoy
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