linux-kernel - Re: [RFC PATCH 0/5] Frequency resolution in CCF vs. cpufreq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKohpokm3WVnu_DggKc4PbhVAKNexrJ4051F-gnVFFTDOyz9ew@mail.gmail.com>
Date:	Thu, 15 May 2014 11:42:09 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Soren Brinkmann <soren.brinkmann@...inx.com>
Cc:	Mike Turquette <mturquette@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Russell King <linux@....linux.org.uk>,
	Michal Simek <michal.simek@...inx.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH 0/5] Frequency resolution in CCF vs. cpufreq

On 15 May 2014 04:00, Soren Brinkmann <soren.brinkmann@...inx.com> wrote:
> I have one or two problems with cpufreq and the CCF, which are caused by
> rounding/different frequency resolutions.
>
> cpufreq works with kHz, while the CCF uses Hz. On Zynq our default frequency is
> 666666666 Hz which the CCF, due to rounding, reports as 666666660. And for
> cpufreq, which simply divides values it obtains through clk_round_rate() by
> 1000, 666666.
> Since passing 666666 to clk_round_rate() does not result in 666666660
> (clk_round_rate() always rounds down!), we chose to put 666667 in the OPP. This
> causes issue 1: cpufreq stats are broken.

I know it might a big exercise, but wouldn't it be worth to make cpufreq start
using frequencies in Hz ?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/