From: Balbir Singh <bsingharora@gmail.com>
To: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
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, devicetree@vger.kernel.org,
Rob Herring <robh+dt@kernel.org>,
mark.rutland@arm.com
Subject: Re: [PATCH v5 4/5] powernv: Pass PSSCR value and mask to power9_idle_stop
Date: Thu, 12 Jan 2017 22:48:02 +0530 [thread overview]
Message-ID: <20170112171802.GB7027@localhost.localdomain> (raw)
In-Reply-To: <1484039224-5630-5-git-send-email-ego@linux.vnet.ibm.com>
On Tue, Jan 10, 2017 at 02:37:03PM +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
>
> The arch300_idle_stop method currently takes only the requested stop
power9_idle_stop (see subject :) and second paragraph)
> 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). For the new firmware, the patch will validate that the invariants
> required by the ISA for the psscr values are maintained by the
> firmware.
>
> This skiboot patch that exports fully populated PSSCR values and the
> mask for all the stop states can be found here:
> https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html
>
> [Optimize the number of instructions before entering STOP with
> ESL=EC=0, validate the PSSCR values provided by the firimware
> maintains the invariants required as per the ISA suggested by Balbir
> Singh]
>
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> ---
Acked-by: Balbir Singh <bsingharora@gmail.com>
next prev parent reply other threads:[~2017-01-12 17:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-10 9:06 [PATCH v5 0/5] powernv:stop: Use psscr_val,mask provided by firmware Gautham R. Shenoy
2017-01-10 9:07 ` [PATCH v5 1/5] powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro Gautham R. Shenoy
2017-01-12 9:42 ` Balbir Singh
2017-01-10 9:07 ` [PATCH v5 2/5] powernv:stop: Uniformly rename power9 to arch300 Gautham R. Shenoy
2017-01-12 9:47 ` Balbir Singh
2017-01-13 3:44 ` Gautham R Shenoy
2017-01-13 3:46 ` Oliver O'Halloran
2017-01-10 9:07 ` [PATCH v5 3/5] cpuidle:powernv: Add helper function to populate powernv idle states Gautham R. Shenoy
2017-01-12 10:04 ` Balbir Singh
2017-01-10 9:07 ` [PATCH v5 4/5] powernv: Pass PSSCR value and mask to power9_idle_stop Gautham R. Shenoy
2017-01-12 17:18 ` Balbir Singh [this message]
2017-01-10 9:07 ` [PATCH v5 5/5] Documentation:powerpc: Add device-tree bindings for power-mgt Gautham R. Shenoy
2017-01-13 16:57 ` Rob Herring
2017-01-25 8:09 ` Gautham R Shenoy
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