From: Baruch Siach <baruch@tkos.co.il>
To: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Emilio Lopez <emilio@elopez.com.ar>,
linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com,
sunny@allwinnertech.com, shuge@allwinnertech.com,
kevin@allwinnertech.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/8] clocksource: sun4i: Add clocksource and sched clock drivers
Date: Thu, 27 Jun 2013 20:36:43 +0300 [thread overview]
Message-ID: <20130627173643.GQ4824@tarshish> (raw)
In-Reply-To: <20130627172144.GD4319@lukather>
Hi Maxime,
On Thu, Jun 27, 2013 at 07:21:44PM +0200, Maxime Ripard wrote:
> On Thu, Jun 27, 2013 at 12:46:49PM +0300, Baruch Siach wrote:
> > On Thu, Jun 27, 2013 at 11:35:58AM +0200, Maxime Ripard wrote:
> > > On Thu, Jun 27, 2013 at 09:02:34AM +0300, Baruch Siach wrote:
> > > > On Wed, Jun 26, 2013 at 11:16:55PM +0200, Maxime Ripard wrote:
> > > > > +static u32 sun4i_timer_sched_read(void)
> > > >
> > > > You commit message mentions "64 bits free running counter", but this one only
> > > > returns 32 bit.
> > >
> > > Yeah, the callback setup by setup_sched_clock is supposed to be
> > > returning a u32, and clocksource_mmio_init only accepts up to 32 bits as
> > > well, so I'm only using the lower 32bits of this 64 bits counter.
> > >
> > > I'll amend the commit log to state this.
> >
> > But using 64 bit counter for sched_clock is much easier that using 32 bit one.
>
> Easier in what aspect? Both API looks similar.
You can just implement your own simple sched_clock() that just returns the
current value of this 64 bit counter, and do away with all the tricky code in
kernel/time/sched_clock.c (in tip.git) that is needed to make the 32 -> 64
extension safe. This is not compatible with multi-platform kernel, though.
> > You can either wait for the rest of Stephen's patch set
> > (http://thread.gmane.org/gmane.linux.ports.arm.msm/4092) before adding 64
> > bit, or you can just make the trivial change to the now generic
> > sched_clock code.
>
> I'll wait for the Stephen's patches to be merged then, and add support
> for 64bits counters to clocksource_mmio_init.
Sound reasonable.
baruch
--
http://baruch.siach.name/blog/ ~. .~ Tk Open Systems
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next prev parent reply other threads:[~2013-06-27 17:36 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 21:16 [PATCH 0/8] clocksource: sunxi: Timer fixes and cleanup Maxime Ripard
2013-06-26 21:16 ` [PATCH 1/8] clocksource: sun4i: Use the BIT macros where possible Maxime Ripard
2013-06-26 21:16 ` [PATCH 2/8] clocksource: sun4i: Add clocksource and sched clock drivers Maxime Ripard
2013-06-26 21:27 ` Daniel Lezcano
2013-06-27 9:31 ` Maxime Ripard
2013-06-27 6:02 ` Baruch Siach
2013-06-27 9:35 ` Maxime Ripard
2013-06-27 9:46 ` Baruch Siach
2013-06-27 17:21 ` Maxime Ripard
2013-06-27 17:36 ` Baruch Siach [this message]
2013-06-27 19:16 ` Maxime Ripard
2013-06-27 10:17 ` [linux-sunxi] " Siarhei Siamashka
2013-06-27 17:02 ` Maxime Ripard
2013-06-27 19:51 ` Siarhei Siamashka
2013-06-28 10:19 ` Maxime Ripard
2013-06-26 21:16 ` [PATCH 3/8] clocksource: sun4i: Don't forget to enable the clock we use Maxime Ripard
2013-06-26 21:16 ` [PATCH 4/8] clocksource: sun4i: Fix the next event code Maxime Ripard
2013-06-26 21:16 ` [PATCH 5/8] clocksource: sun4i: Factor out some timer code Maxime Ripard
2013-06-26 21:16 ` [PATCH 6/8] clocksource: sun4i: Remove TIMER_SCAL variable Maxime Ripard
2013-06-26 21:17 ` [PATCH 7/8] clocksource: sun4i: Cleanup parent clock setup Maxime Ripard
2013-06-26 21:17 ` [PATCH 8/8] clocksource: sun4i: Fix bug when switching from periodic to oneshot modes Maxime Ripard
2013-06-27 9:27 ` [linux-sunxi] [PATCH 0/8] clocksource: sunxi: Timer fixes and cleanup Hans de Goede
2013-06-27 9:43 ` Maxime Ripard
2013-06-27 9:54 ` Hans de Goede
2013-06-27 16:54 ` Maxime Ripard
2013-06-27 18:13 ` Hans de Goede
2013-06-28 10:41 ` Maxime Ripard
2013-06-27 20:26 ` Siarhei Siamashka
2013-06-28 8:17 ` Hans de Goede
[not found] ` <2013062809433715678058@allwinnertech.com>
[not found] ` <20130628124843.242df804@i7>
2013-06-28 10:26 ` Thomas Gleixner
2013-06-28 11:14 ` Siarhei Siamashka
2013-06-28 14:02 ` Thomas Gleixner
2013-06-28 17:03 ` maxime.ripard
[not found] ` <20130628132912.014b2f5b@i7>
2013-06-28 14:16 ` maxime.ripard
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