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Message-ID: <20230821045928.1350893-1-vaibhav@linux.ibm.com>
Date: Mon, 21 Aug 2023 10:29:27 +0530
From: Vaibhav Jain <vaibhav@...ux.ibm.com>
To: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org
Cc: Vaibhav Jain <vaibhav@...ux.ibm.com>,
Jonathan Corbet <corbet@....net>,
Michael Ellerman <mpe@...erman.id.au>,
Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
"Paul E. McKenney" <paulmck@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Randy Dunlap <rdunlap@...radead.org>,
Peter Zijlstra <peterz@...radead.org>,
"Steven Rostedt (Google)" <rostedt@...dmis.org>,
Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
Subject: [PATCH v2] powerpc: Enable generic cpu idle-loop
This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch
powerpc. This should add support for kernel param 'nohlt'.
Powerpc kernel also supports another kernel boot-time param called
'powersave' which can also be used to disable all cpu idle-states and
forces CPU to an idle-loop similar to what cpu_idle_poll() does. Hence this
patch also updates the handling of 'powersave=off' kernel param to enable
generic cpu idle-loop if its enabled.
Signed-off-by: Vaibhav Jain<vaibhav@...ux.ibm.com>
---
Changelog:
Since v1:
https://lore.kernel.org/all/20230818050739.827851-1-vaibhav@linux.ibm.com
* Updated powersave_off() to enable generic cpu idle-loop if
'powersave=off' kernel arg is given. [Mpe]
* Update patch description
---
Documentation/admin-guide/kernel-parameters.txt | 2 +-
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/idle.c | 3 +++
3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 722b6eca2e93..6b657ebafcfb 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3738,7 +3738,7 @@
nohibernate [HIBERNATION] Disable hibernation and resume.
- nohlt [ARM,ARM64,MICROBLAZE,MIPS,SH] Forces the kernel to
+ nohlt [ARM,ARM64,MICROBLAZE,MIPS,PPC,SH] Forces the kernel to
busy wait in do_idle() and not use the arch_cpu_idle()
implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
to be effective. This is useful on platforms where the
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 0b1172cbeccb..574661403800 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -193,6 +193,7 @@ config PPC
select GENERIC_CPU_VULNERABILITIES if PPC_BARRIER_NOSPEC
select GENERIC_EARLY_IOREMAP
select GENERIC_GETTIMEOFDAY
+ select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_PCI_IOMAP if PCI
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index b1c0418b25c8..7367a0698459 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -21,6 +21,7 @@
#include <linux/cpu.h>
#include <linux/sysctl.h>
#include <linux/tick.h>
+#include <linux/cpu.h>
#include <asm/processor.h>
#include <asm/cputable.h>
@@ -35,6 +36,8 @@ EXPORT_SYMBOL(cpuidle_disable);
static int __init powersave_off(char *arg)
{
+ /* Use generic idle loop if thats available */
+ cpu_idle_poll_ctrl(true);
ppc_md.power_save = NULL;
cpuidle_disable = IDLE_POWERSAVE_OFF;
return 1;
--
2.41.0
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