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 CAED9288CC; Thu, 23 Jan 2025 12:16:55 +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=1737634617; cv=none; b=YOkqmBPCSS3k0tyEafDpqQC40UTfZ40MKKftq9x4Jfi9rS7HeZqdnGTVaTOngF8hdWUZWTlHz6whiII9VHnzr62RI9F6RMy3DaTNllHmTyHROKrzcCgjXsP2XI8NkkTBdCZXE7uFY2Ldo5lj+X3JXRRt2xtBamiRhIoOazR1CME= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737634617; c=relaxed/simple; bh=yLwUUzeSvSmXldYU6OqHdpQgkd63gnwoGcDdnEPqR7Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MjRRm+5lWNJqyKaMvqIUA4P35c7FzreFPaP02XLIWc71uT5q4pjx9mSj1yMU6woxW06SimSV7ji+HAakL3NQ3bNLWLGPqq2dac34Hx8z/k4iM+GlgFk/6VqXlL0rleNoMdPah4hiAy3digiY/IofOYjsuiErhSLNpR1YMXyLi6c= 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 531861063; Thu, 23 Jan 2025 04:17:23 -0800 (PST) Received: from bogus (e133711.arm.com [10.1.196.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 33A133F5A1; Thu, 23 Jan 2025 04:16:53 -0800 (PST) Date: Thu, 23 Jan 2025 12:16:50 +0000 From: Sudeep Holla To: Dan Carpenter Cc: zuoqian , Ionela Voinescu , rafael@kernel.org, Sudeep Holla , viresh.kumar@linaro.org, cristian.marussi@arm.com, arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cpufreq: scpi: compare against frequency instead of rate Message-ID: References: <20250123075321.4442-1-zuoqian113@gmail.com> Precedence: bulk X-Mailing-List: arm-scmi@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: (for some reason I don't have the original email) On Thu, Jan 23, 2025 at 02:12:14PM +0300, Dan Carpenter wrote: > On Thu, Jan 23, 2025 at 07:53:20AM +0000, zuoqian wrote: > > The CPU rate from clk_get_rate() may not be divisible by 1000 > > (e.g., 133333333). But the rate calculated from frequency is always > > divisible by 1000 (e.g., 133333000). > > Comparing the rate causes a warning during CPU scaling: > > "cpufreq: __target_index: Failed to change cpu frequency: -5". > > When we choose to compare frequency here, the issue does not occur. > > > > Signed-off-by: zuoqian > > --- > > drivers/cpufreq/scpi-cpufreq.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c > > index cd89c1b9832c..3bff4bb5ab4a 100644 > > --- a/drivers/cpufreq/scpi-cpufreq.c > > +++ b/drivers/cpufreq/scpi-cpufreq.c > > @@ -39,8 +39,9 @@ static unsigned int scpi_cpufreq_get_rate(unsigned int cpu) > > static int > > scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) > > { > > - u64 rate = policy->freq_table[index].frequency * 1000; > > policy->freq_table[index].frequency is a u32 so in this original > calculation, even though "rate" is declared as a u64, it can't actually > be more than UINT_MAX. > Agreed and understood. > > + unsigned long freq = policy->freq_table[index].frequency; > > struct scpi_data *priv = policy->driver_data; > > + u64 rate = freq * 1000; > > So you've fixed this by casting policy->freq_table[index].frequency > to unsigned long, which fixes the problem on 64bit systems but it still > remains on 32bit systems. It would be better to declare freq as a u64. > Just trying to understand if that matters. freq is in kHz as copied from policy->freq_table[index].frequency and we compare it with kHZ below as the obtained clock rate is divided by 1000. What am I missing ? If it helps, it can be renamed as freq_in_khz and even keep it as "unsigned int" as in struct cpufreq_frequency_table. -- Regards, Sudeep