From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Mike Turquette <mturquette@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Russell King <linux@arm.linux.org.uk>,
Michal Simek <michal.simek@xilinx.com>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
cpufreq@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH 0/5] Frequency resolution in CCF vs. cpufreq
Date: Thu, 15 May 2014 09:47:24 +0200 [thread overview]
Message-ID: <20140515074724.GJ16662@pengutronix.de> (raw)
In-Reply-To: <1400106655-22465-1-git-send-email-soren.brinkmann@xilinx.com>
On Wed, May 14, 2014 at 03:30:50PM -0700, Soren Brinkmann wrote:
> Hi,
>
> 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
Why does this happen? Isn't that a bug? What is the actual freqency?
666666666 Hz or 2000000000/3 Hz?
> 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
What is OPP?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
next prev parent reply other threads:[~2014-05-15 7:47 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-14 22:30 [RFC PATCH 0/5] Frequency resolution in CCF vs. cpufreq Soren Brinkmann
2014-05-14 22:30 ` [RFC PATCH 1/5] cpufreq: stats: Allow small rounding errors Soren Brinkmann
2014-05-14 22:30 ` [RFC PATCH 2/5] clk: Introduce 'clk_round_rate_nearest()' Soren Brinkmann
2014-05-15 7:38 ` Uwe Kleine-König
2014-05-15 14:10 ` Sören Brinkmann
2014-05-19 0:51 ` Sören Brinkmann
2014-05-19 16:19 ` Uwe Kleine-König
2014-05-19 16:41 ` Sören Brinkmann
2014-05-19 17:29 ` Sören Brinkmann
2014-05-20 7:51 ` Uwe Kleine-König
2014-05-20 7:33 ` Uwe Kleine-König
2014-05-20 16:01 ` Sören Brinkmann
2014-05-20 17:48 ` Stephen Boyd
2014-05-20 21:48 ` Sören Brinkmann
2014-05-21 7:34 ` Uwe Kleine-König
2014-05-21 15:58 ` Sören Brinkmann
2014-05-21 18:23 ` Uwe Kleine-König
2014-05-21 20:19 ` Sören Brinkmann
2014-05-21 20:33 ` Mike Turquette
2014-05-22 18:03 ` Sören Brinkmann
2014-05-22 18:20 ` Uwe Kleine-König
2014-05-22 20:32 ` Sören Brinkmann
2014-05-22 21:03 ` Mike Turquette
2014-05-22 23:44 ` Sören Brinkmann
2014-05-23 1:37 ` Mike Turquette
2014-05-23 16:14 ` Sören Brinkmann
2014-05-26 6:29 ` Viresh Kumar
2014-05-26 11:22 ` Rafael J. Wysocki
2014-05-26 11:07 ` Viresh Kumar
2014-05-26 11:47 ` Rafael J. Wysocki
2014-05-26 21:52 ` Sören Brinkmann
2014-05-28 2:05 ` Mike Turquette
2014-05-28 16:17 ` Rafael J. Wysocki
2014-06-07 0:44 ` Sören Brinkmann
2014-05-14 22:30 ` [RFC PATCH 3/5] cpufreq: cpu0: Use clk_round_rate_nearest() Soren Brinkmann
2014-05-14 22:30 ` [RFC PATCH 4/5] ARM: zynq: dt: Use properly rounded frequencies in OPPs Soren Brinkmann
2014-05-14 22:30 ` [RFC PATCH 5/5] net: macb: Use clk_round_rate_nearest() API Soren Brinkmann
2014-05-15 6:12 ` [RFC PATCH 0/5] Frequency resolution in CCF vs. cpufreq Viresh Kumar
2014-05-15 14:05 ` Sören Brinkmann
2014-05-15 7:47 ` Uwe Kleine-König [this message]
2014-05-15 12:14 ` Nishanth Menon
2014-05-15 14:00 ` Sören Brinkmann
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