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Mon, 27 Apr 2020 13:48:46 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 545B57805C; Mon, 27 Apr 2020 13:48:45 +0000 (GMT) Received: from sofia.ibm.com (unknown [9.85.94.115]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 27 Apr 2020 13:48:45 +0000 (GMT) Received: by sofia.ibm.com (Postfix, from userid 1000) id 42B5F2E2E25; Mon, 27 Apr 2020 19:18:40 +0530 (IST) Date: Mon, 27 Apr 2020 19:18:40 +0530 From: Gautham R Shenoy To: Abhishek Goel Subject: Re: [RFC 3/3] powernv/cpuidle : Introduce capability for firmware-enabled-stop Message-ID: <20200427134840.GE29708@in.ibm.com> References: <20200427021027.114582-1-huntbag@linux.vnet.ibm.com> <20200427021027.114582-3-huntbag@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200427021027.114582-3-huntbag@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-27_09:2020-04-24, 2020-04-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 mlxlogscore=999 priorityscore=1501 phishscore=0 mlxscore=0 adultscore=0 lowpriorityscore=0 impostorscore=0 clxscore=1015 malwarescore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004270114 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: ego@linux.vnet.ibm.com Cc: ego@linux.vnet.ibm.com, mikey@neuling.org, linux-kernel@vger.kernel.org, npiggin@gmail.com, linuxppc-dev@ozlabs.org, oohall@gmail.com, psampat@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Apr 26, 2020 at 09:10:27PM -0500, Abhishek Goel wrote: > This patch introduces the capability for firmware to handle the stop > states instead. A bit is set based on the discovery of the feature > and correspondingly also the responsibility to handle the stop states. > > If Kernel does not know about stop version, it can fallback to opal for > idle stop support if firmware-stop-supported property is present. > > Earlier this patch was posted as part of this series : > https://lkml.org/lkml/2020/3/4/589 > > Signed-off-by: Pratik Rajesh Sampat > Signed-off-by: Abhishek Goel > --- > > v1->v2: This patch is newly added in this series. > > arch/powerpc/include/asm/processor.h | 1 + > arch/powerpc/kernel/dt_cpu_ftrs.c | 8 ++++++++ > arch/powerpc/platforms/powernv/idle.c | 27 ++++++++++++++++----------- > 3 files changed, 25 insertions(+), 11 deletions(-) > > diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h > index 66fa20476d0e..d5c6532b11ef 100644 > --- a/arch/powerpc/include/asm/processor.h > +++ b/arch/powerpc/include/asm/processor.h > @@ -430,6 +430,7 @@ extern unsigned long cpuidle_disable; > enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF}; > > #define STOP_ENABLE 0x00000001 > +#define FIRMWARE_STOP_ENABLE 0x00000010 > > #define STOP_VERSION_P9 0x1 > > diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c > index db1a525e090d..ff4a87b79702 100644 > --- a/arch/powerpc/kernel/dt_cpu_ftrs.c > +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c > @@ -298,6 +298,13 @@ static int __init feat_enable_idle_stop(struct dt_cpu_feature *f) > return 1; > } > > +static int __init feat_enable_firmware_stop(struct dt_cpu_feature *f) > +{ > + stop_dep.cpuidle_prop |= FIRMWARE_STOP_ENABLE; > + > + return 1; > +} > + > static int __init feat_enable_mmu_hash(struct dt_cpu_feature *f) > { > u64 lpcr; > @@ -592,6 +599,7 @@ static struct dt_cpu_feature_match __initdata > {"idle-nap", feat_enable_idle_nap, 0}, > {"alignment-interrupt-dsisr", feat_enable_align_dsisr, 0}, > {"idle-stop", feat_enable_idle_stop, 0}, > + {"firmware-stop-supported", feat_enable_firmware_stop, 0}, > {"machine-check-power8", feat_enable_mce_power8, 0}, > {"performance-monitor-power8", feat_enable_pmu_power8, 0}, > {"data-stream-control-register", feat_enable_dscr, CPU_FTR_DSCR}, > diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c > index 538f0842ac3f..0de5de81902e 100644 > --- a/arch/powerpc/platforms/powernv/idle.c > +++ b/arch/powerpc/platforms/powernv/idle.c > @@ -633,16 +633,6 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on) > unsigned long mmcr0 = 0; > struct p9_sprs sprs = {}; /* avoid false used-uninitialised */ > bool sprs_saved = false; > - int rc = 0; > - > - /* > - * Kernel takes decision whether to make OPAL call or not. This logic > - * will be combined with the logic for BE opal to take decision. > - */ > - if (firmware_stop_supported) { > - rc = opal_cpu_idle(cpu_to_be64(__pa(&srr1)), (uint64_t) psscr); > - goto out; > - } > > if (!(psscr & (PSSCR_EC|PSSCR_ESL))) { > /* EC=ESL=0 case */ > @@ -835,6 +825,19 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on) > return srr1; > } > > +static unsigned long power9_firmware_idle_stop(unsigned long psscr, bool mmu_on) > +{ > + unsigned long srr1; > + int rc; > + > + rc = opal_cpu_idle(cpu_to_be64(__pa(&srr1)), (uint64_t) psscr); > + > + if (mmu_on) > + mtmsr(MSR_KERNEL); > + return srr1; > + > +} > + > #ifdef CONFIG_HOTPLUG_CPU > static unsigned long power9_offline_stop(unsigned long psscr) > { > @@ -1394,9 +1397,11 @@ static int __init pnv_init_idle_states(void) > !(stop_dep.cpuidle_prop & STOP_ENABLE)) > goto out; > > - /* Check for supported version in kernel */ > + /* Check for supported version in kernel or fallback to kernel*/ > if (stop_dep.stop_version & STOP_VERSION_P9) { > stop_dep.idle_stop = power9_idle_stop; > + } else if (stop_dep.cpuidle_prop & FIRMWARE_STOP_ENABLE) { > + stop_dep.idle_stop = power9_firmware_idle_stop; Ok, so in this patch you first check if the "idle-stop" feature is available. Only otherwise you fallback to the OPAL based cpuidle driver. This looks ok to me. > } else { > stop_dep.idle_stop = NULL; > goto out; > -- > 2.17.1 > -- Thanks and Regards gautham.