From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Paul Walmsley <paul@pwsan.com>, Stephen Boyd <sboyd@codeaurora.org>
Cc: "Mike Turquette" <mturquette@linaro.org>,
linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
"Jonathan Corbet" <corbet@lwn.net>,
"Shawn Guo" <shawn.guo@linaro.org>,
"ascha Hauer" <kernel@pengutronix.de>,
"David Brown" <davidb@codeaurora.org>,
"Daniel Walker" <dwalker@fifo99.com>,
"Bryan Huntsman" <bryanh@codeaurora.org>,
"Tony Lindgren" <tony@atomide.com>,
"Liviu Dudau" <liviu.dudau@arm.com>,
"Sudeep Holla" <sudeep.holla@arm.com>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Ralf Baechle" <ralf@linux-mips.org>,
"Max Filippov" <jcmvbkbc@gmail.com>,
"Heiko Stuebner" <heiko@sntech.de>,
"Sylwester Nawrocki" <s.nawrocki@samsung.com>,
"Tomasz Figa" <tomasz.figa@gmail.com>,
"Barry Song" <baohua@kernel.org>,
"Viresh Kumar" <viresh.linux@gmail.com>,
"Emilio López" <emilio@elopez.com.ar>,
"Maxime Ripard" <maxime.ripard@free-electrons.com>,
"Peter De Schrijver" <pdeschrijver@nvidia.com>,
"Prashant Gaikwad" <pgaikwad@nvidia.com>,
"Stephen Warren" <swarren@wwwdotorg.org>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Alexandre Courbot" <gnurou@gmail.com>,
"Tero Kristo" <t-kristo@ti.com>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Michal Simek" <michal.simek@xilinx.com>,
"Philipp Zabel" <p.zabel@pengutronix.de>,
linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, linux-omap@vger.kernel.org,
linux-mips@linux-mips.org, patches@opensource.wolfsonmicro.com,
linux-rockchip@lists.infradead.org,
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linux-tegra@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-media@vger.kernel.org, rtc-linux@googlegroups.com
Subject: Re: [PATCH v2 1/2] clk: change clk_ops' ->round_rate() prototype
Date: Fri, 5 Jun 2015 13:38:03 +0200 [thread overview]
Message-ID: <20150605133803.59990a66@bbrezillon> (raw)
In-Reply-To: <alpine.DEB.2.02.1506042258530.12316@utopia.booyaka.com>
Hi Paul,
On Thu, 4 Jun 2015 23:02:25 +0000 (UTC)
Paul Walmsley <paul@pwsan.com> wrote:
> Hi folks
>
> just a brief comment on this one:
>
> On Thu, 30 Apr 2015, Boris Brezillon wrote:
>
> > Clock rates are stored in an unsigned long field, but ->round_rate()
> > (which returns a rounded rate from a requested one) returns a long
> > value (errors are reported using negative error codes), which can lead
> > to long overflow if the clock rate exceed 2Ghz.
> >
> > Change ->round_rate() prototype to return 0 or an error code, and pass the
> > requested rate as a pointer so that it can be adjusted depending on
> > hardware capabilities.
>
> ...
>
> > diff --git a/Documentation/clk.txt b/Documentation/clk.txt
> > index 0e4f90a..fca8b7a 100644
> > --- a/Documentation/clk.txt
> > +++ b/Documentation/clk.txt
> > @@ -68,8 +68,8 @@ the operations defined in clk.h:
> > int (*is_enabled)(struct clk_hw *hw);
> > unsigned long (*recalc_rate)(struct clk_hw *hw,
> > unsigned long parent_rate);
> > - long (*round_rate)(struct clk_hw *hw,
> > - unsigned long rate,
> > + int (*round_rate)(struct clk_hw *hw,
> > + unsigned long *rate,
> > unsigned long *parent_rate);
> > long (*determine_rate)(struct clk_hw *hw,
> > unsigned long rate,
>
> I'd suggest that we should probably go straight to 64-bit rates. There
> are already plenty of clock sources that can generate rates higher than
> 4GiHz.
Yep, that was something I was considering too. If Stephen agrees I'll
change that in the next version.
BTW, you're referring to the second version of this patch, but things
have changed a bit: Stephen recommended to only modify the
->determine_rate() prototype and pass a structure instead of a list of
arguments.
Here is the last version of this series [1].
Best Regards,
Boris
[1]http://patchwork.linux-mips.org/patch/10092/
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-06-05 11:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-30 15:30 [PATCH v2 0/2] clk: adapt ->round_rate()/->determine_rate() prototypes Boris Brezillon
2015-04-30 15:30 ` [PATCH v2 1/2] clk: change clk_ops' ->round_rate() prototype Boris Brezillon
2015-05-07 6:39 ` Stephen Boyd
2015-05-07 7:37 ` Boris Brezillon
2015-05-15 15:40 ` Boris Brezillon
2015-05-16 11:14 ` Mikko Perttunen
2015-05-20 1:01 ` Stephen Boyd
2015-06-04 23:02 ` Paul Walmsley
2015-06-05 8:46 ` Jon Hunter
2015-06-05 11:39 ` Boris Brezillon
2015-06-08 8:46 ` Jon Hunter
2015-06-05 11:38 ` Boris Brezillon [this message]
2015-04-30 15:30 ` [PATCH v2 2/2] clk: change clk_ops' ->determine_rate() prototype Boris Brezillon
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