From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 77DE2C02182 for ; Tue, 21 Jan 2025 15:28:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=0kdbhR5Oah3F6JdgY3wvRdCOu+Dio2Yu26Rr1uZmLOE=; b=RTFn9CArnmqPPR+6dfY5soeOtl 4Bm8HPtucsM7o6Et8vZOhdku14UaXcGDDKA6zlrW0wPfvXK8UsbTS2Z6USImnkeUGziI0VeeR5yHZ 5Ahk6DbSRbS+Sr86v3YUZpkQFNpuPl8NviIrWiGy8RAdgIrOfMTYz3PcQON/eLp/KKNAGNKgeeoBq ofWW8JuSN/8i/SLGH8BQBY8qlrnpkj5BQgWWZe/Yc55N0Ldi1HeRoI1aq89le+apyB6eVbDPkfvHi AyVWI91jsXeXP6quHTrzc17bQb4yVKIpxyCs0QNQtMcCeffU6ki0v8jrqG3+fUA2dHV5462Em4+3L ndUKDYKg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1taGAN-00000008DVI-2GSC; Tue, 21 Jan 2025 15:27:47 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1taFyL-00000008Bcp-0BMj for linux-arm-kernel@lists.infradead.org; Tue, 21 Jan 2025 15:15:22 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C7ED31063; Tue, 21 Jan 2025 07:15:48 -0800 (PST) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BB5E33F66E; Tue, 21 Jan 2025 07:15:16 -0800 (PST) Date: Tue, 21 Jan 2025 16:14:32 +0100 From: Beata Michalska To: Viresh Kumar Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, ionela.voinescu@arm.com, sudeep.holla@arm.com, will@kernel.org, catalin.marinas@arm.com, rafael@kernel.org, sumitg@nvidia.com, yang@os.amperecomputing.com, vanshikonda@os.amperecomputing.com, lihuisong@huawei.com, zhanjie9@hisilicon.com Subject: Re: [PATCH v9 1/5] cpufreq: Allow arch_freq_get_on_cpu to return an error Message-ID: References: <20250121084435.2839280-1-beata.michalska@arm.com> <20250121084435.2839280-2-beata.michalska@arm.com> <20250121104706.2gcegucb6hcuksrd@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250121104706.2gcegucb6hcuksrd@vireshk-i7> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250121_071521_172173_0349454E X-CRM114-Status: GOOD ( 22.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 21, 2025 at 04:17:06PM +0530, Viresh Kumar wrote: > On 21-01-25, 08:44, Beata Michalska wrote: > > Allow arch_freq_get_on_cpu to return an error for cases when retrieving > > current CPU frequency is not possible, whether that being due to lack of > > required arch support or due to other circumstances when the current > > frequency cannot be determined at given point of time. > > > > Signed-off-by: Beata Michalska > > --- > > arch/x86/kernel/cpu/aperfmperf.c | 2 +- > > arch/x86/kernel/cpu/proc.c | 7 +++++-- > > drivers/cpufreq/cpufreq.c | 8 ++++---- > > include/linux/cpufreq.h | 2 +- > > 4 files changed, 11 insertions(+), 8 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c > > index f642de2ebdac..6cf31a1649c4 100644 > > --- a/arch/x86/kernel/cpu/aperfmperf.c > > +++ b/arch/x86/kernel/cpu/aperfmperf.c > > @@ -498,7 +498,7 @@ void arch_scale_freq_tick(void) > > */ > > #define MAX_SAMPLE_AGE ((unsigned long)HZ / 50) > > > > -unsigned int arch_freq_get_on_cpu(int cpu) > > +int arch_freq_get_on_cpu(int cpu) > > { > > struct aperfmperf *s = per_cpu_ptr(&cpu_samples, cpu); > > unsigned int seq, freq; > > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c > > index 41ed01f46bd9..d79f5845a463 100644 > > --- a/arch/x86/kernel/cpu/proc.c > > +++ b/arch/x86/kernel/cpu/proc.c > > @@ -86,9 +86,12 @@ static int show_cpuinfo(struct seq_file *m, void *v) > > seq_printf(m, "microcode\t: 0x%x\n", c->microcode); > > > > if (cpu_has(c, X86_FEATURE_TSC)) { > > - unsigned int freq = arch_freq_get_on_cpu(cpu); > > + int freq = arch_freq_get_on_cpu(cpu); > > > > - seq_printf(m, "cpu MHz\t\t: %u.%03u\n", freq / 1000, (freq % 1000)); > > + if (freq <= 0) > > + seq_puts(m, "cpu MHz\t\t: Unknown\n"); > > + else > > + seq_printf(m, "cpu MHz\t\t: %u.%03u\n", freq / 1000, (freq % 1000)); > > } > > > > /* Cache size */ > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 418236fef172..6f45684483c4 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -728,18 +728,18 @@ show_one(cpuinfo_transition_latency, cpuinfo.transition_latency); > > show_one(scaling_min_freq, min); > > show_one(scaling_max_freq, max); > > > > -__weak unsigned int arch_freq_get_on_cpu(int cpu) > > +__weak int arch_freq_get_on_cpu(int cpu) > > { > > - return 0; > > + return -EOPNOTSUPP; > > } > > > > static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf) > > { > > ssize_t ret; > > - unsigned int freq; > > + int freq; > > > > freq = arch_freq_get_on_cpu(policy->cpu); > > - if (freq) > > + if (freq > 0) > > >= ? > > Since we can return error now, 0 should be considered a valid > frequency value ? Theoretically speaking - it should, though what would 0 actually represent then ? --- BR Beata > > > ret = sysfs_emit(buf, "%u\n", freq); > > else if (cpufreq_driver->setpolicy && cpufreq_driver->get) > > ret = sysfs_emit(buf, "%u\n", cpufreq_driver->get(policy->cpu)); > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > > index 7fe0981a7e46..02fd4746231d 100644 > > --- a/include/linux/cpufreq.h > > +++ b/include/linux/cpufreq.h > > @@ -1184,7 +1184,7 @@ static inline int of_perf_domain_get_sharing_cpumask(int pcpu, const char *list_ > > } > > #endif > > > > -extern unsigned int arch_freq_get_on_cpu(int cpu); > > +extern int arch_freq_get_on_cpu(int cpu); > > > > #ifndef arch_set_freq_scale > > static __always_inline > > -- > > 2.25.1 > > -- > viresh