From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 62184EBE; Tue, 21 Jan 2025 15:15:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737472523; cv=none; b=oIJXhxn5BzXVv4DdM3L82Bsyfk+e9D3uPTQBBBXr4aQCbK1Ap1sYDP22NkZucVBMjSl5xPstkJSc+dDVr0YnnQINCymwMnmV1khm+CsreF09Ac7UTs4VhbqdFzaFUaHXSjuAogT6s8rBR3qR5kCBg5JBxoMGhjWTlpVXpbvXCFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737472523; c=relaxed/simple; bh=+n+sIJXaTD1gGUpYrtaMwNZ9Xm0JBUHoumwhed+5Nao=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GylwHNhx7VKyqAEgHRKjj88/7wqWljNSzw9SPefHsbaLMAGVqWdBCLq2CTgvJh4XqBPOKsG9oKl4yAMfE8Rob9Ocas7GZZy5f1GbhtbyJJapSlM5nALjI60QPjyVTYSN4fXHb9qCodJ+CWdkE/x3pz/GQp6dZVgOnHs0526bHsA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250121104706.2gcegucb6hcuksrd@vireshk-i7> 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