linux-kernel - [PATCH 0/6] Enable support for deep-stop states on POWER9

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Date:   Tue, 16 May 2017 14:19:42 +0530
From:   "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
To:     Nicholas Piggin <npiggin@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        Akshay Adiga <akshay.adiga@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
Subject: [PATCH 0/6] Enable support for deep-stop states on POWER9

From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>

Hi,

This patch series contains some of the fixes required for enabling
support for deep stop states such as STOP4 and STOP11 via CPU-Hotplug.

These fixes mainly ensure that some of the hypervisor resources which
are lost during the deep stop state are correctly restored on a
wakeup.

There are 6 patches in the series.

Patch 1 correctly initializes the core_idle_state_ptr based on the
threads_per_core. core_idle_state_ptr is used to determine if a thread
is the last thread entering a deep stop state or a first thread waking
up from deep stop state in order to save/restore per-core resources.

Patch 2 decouples restoring timebase from restoring hypervisor
resources, as there are stop states which lose hypervisor state but
not the timebase.

Patch 3 saves the LPCR value before executing deep stop and restores
it back to the saved value on the wakeup from stop.

Patch 4 programs the restoration of some of one-time initialized SPRs
via the stop-api.

Patch 5 provides a workaround for a hardware issue on POWER9 DD1 chips
where the PLS value cannot be relied upon on a wakeup from deep stop.

Patch 6 fixes the cpuidle-powernv initialization code to allow deep
states that don't lose timebase.

These patches are based on the Linux upstream and have been tested
with the corresponding skiboot patches in
https://lists.ozlabs.org/pipermail/skiboot/2017-May/007183.html to get
STOP4 working via CPU-Hotplug.

Akshay Adiga (1):
  powernv:idle: Restore SPRs for deep idle states via stop API.

Gautham R. Shenoy (5):
  powernv:idle: Correctly initialize core_idle_state_ptr
  powernv:idle: Decouple Timebase restore & Per-core SPRs restore
  powernv:idle: Restore LPCR on wakeup from deep-stop
  powernv:idle: Use Requested Level for restoring state on P9 DD1
  cpuidle-powernv: Allow Deep stop states that don't stop time

 arch/powerpc/include/asm/paca.h       |   2 +
 arch/powerpc/kernel/asm-offsets.c     |   1 +
 arch/powerpc/kernel/idle_book3s.S     |  33 +++++++---
 arch/powerpc/platforms/powernv/idle.c | 112 +++++++++++++++++++++-------------
 drivers/cpuidle/cpuidle-powernv.c     |  16 +++--
 5 files changed, 110 insertions(+), 54 deletions(-)

-- 
1.8.3.1