Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756028AbdCTQwI (ORCPT ); Mon, 20 Mar 2017 12:52:08 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:34834 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755975AbdCTQtX (ORCPT ); Mon, 20 Mar 2017 12:49:23 -0400 Date: Tue, 21 Mar 2017 02:39:34 +1000 From: Nicholas Piggin To: "Gautham R. Shenoy" Cc: Michael Ellerman , Michael Neuling , Benjamin Herrenschmidt , "Shreyas B. Prabhu" , Shilpasri G Bhat , Vaidyanathan Srinivasan , Anton Blanchard , Balbir Singh , Akshay Adiga , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH 3/4] powernv:idle: Don't override default/deepest directly in kernel Message-ID: <20170321023934.1a9b84f6@roar.ozlabs.ibm.com> In-Reply-To: <84bfbacbd0ab98dd82241292a29e4d5d1bb456c6.1490024477.git.ego@linux.vnet.ibm.com> References: <84bfbacbd0ab98dd82241292a29e4d5d1bb456c6.1490024477.git.ego@linux.vnet.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2799 Lines: 72 On Mon, 20 Mar 2017 21:24:17 +0530 "Gautham R. Shenoy" wrote: > From: "Gautham R. Shenoy" > > Currently during idle-init on power9, if we don't find suitable stop > states in the device tree that can be used as the > default_stop/deepest_stop, we set stop0 (ESL=1,EC=1) as the default > stop state psscr to be used by power9_idle and deepest stop state > which is used by CPU-Hotplug. > > However, if the platform firmware has not configured or enabled a stop > state, the kernel should not make any assumptions and fallback to a > default choice. > > If the kernel uses a stop state that is not configured by the platform > firmware, it may lead to further failures which should be avoided. > > In this patch, we modify the init code to ensure that the kernel uses > only the stop states exposed by the firmware through the device > tree. When a suitable default stop state isn't found, we disable > ppc_md.power_save for power9. Similarly, when a suitable > deepest_stop_state is not found in the device tree exported by the > firmware, fall back to the default busy-wait loop in the CPU-Hotplug > code. > > [Changelog written with inputs from svaidy@linux.vnet.ibm.com] > > Signed-off-by: Gautham R. Shenoy > --- > arch/powerpc/platforms/powernv/idle.c | 35 ++++++++++++++++++----------------- > 1 file changed, 18 insertions(+), 17 deletions(-) > > diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c > index f335e0f..63ade78 100644 > --- a/arch/powerpc/platforms/powernv/idle.c > +++ b/arch/powerpc/platforms/powernv/idle.c > @@ -147,7 +147,6 @@ u32 pnv_get_supported_cpuidle_states(void) > } > EXPORT_SYMBOL_GPL(pnv_get_supported_cpuidle_states); > > - > static void pnv_fastsleep_workaround_apply(void *info) > > { > @@ -241,8 +240,9 @@ static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600, > * The default stop state that will be used by ppc_md.power_save > * function on platforms that support stop instruction. > */ > -u64 pnv_default_stop_val; > -u64 pnv_default_stop_mask; > +static u64 pnv_default_stop_val; > +static u64 pnv_default_stop_mask; > +static bool default_stop_found; > > /* > * Used for ppc_md.power_save which needs a function with no parameters > @@ -262,8 +262,9 @@ static void power9_idle(void) > * psscr value and mask of the deepest stop idle state. > * Used when a cpu is offlined. > */ > -u64 pnv_deepest_stop_psscr_val; > -u64 pnv_deepest_stop_psscr_mask; > +static u64 pnv_deepest_stop_psscr_val; > +static u64 pnv_deepest_stop_psscr_mask; > +static bool deepest_stop_found; Aha you have made them static. Nitpick withdrawn :) The log messages look good now. Reviewed-by: Nicholas Piggin