From: Finn Thain <fthain@telegraphics.com.au>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
funaho@jurai.org, schwab@linux-m68k.org,
Arnd Bergmann <arnd@arndb.de>,
schivers@csc.com.au, Thomas Gleixner <tglx@linutronix.de>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
schmitzmic@gmail.com, John Stultz <john.stultz@linaro.org>,
linux-m68k@lists.linux-m68k.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v2 10/14] m68k: mac: Convert to clocksource API
Date: Tue, 20 Nov 2018 20:00:32 +1100 (AEDT) [thread overview]
Message-ID: <alpine.LNX.2.21.1811201925020.258@nippy.intranet> (raw)
In-Reply-To: <CACRpkdZdJDYaOi1HeMiS2hkjOf0gjQphGXy-Ka+m=1LbDCXPfA@mail.gmail.com>
On Tue, 20 Nov 2018, Linus Walleij wrote:
> On Mon, Nov 19, 2018 at 2:22 AM Finn Thain <fthain@telegraphics.com.au> wrote:
>
> > Add a platform clocksource by adapting the existing arch_gettimeoffset
> > implementation.
> >
> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> > Acked-by: Linus Walleij <linus.walleij@linaro.org>
> > Tested-by: Stan Johnson <userm57@yahoo.com>
>
> As noted for the Amiga CIA (which is pretty much a sibling to this MOS
> 6522 VIA) this chip also has two counters and could use one as
> clocksource and the other as clock event.
>
> Again I bet this is just using one timer out of habit.
>
> It will be an easy feat to make a clean clocksource+clock event for this
> hardware as well once this refactoring is complete.
>
Right. Both timer 1 and timer 2 have a timed interrupt mode, and either
could probably serve as a clock event device or a clocksource. Some Mac
models have a second VIA with two more timers, but not all.
(As clock event devices, the longest interval you can program is about 83
ms. As 783360 Hz, 16-bit clocksources, they wrap about 12 times every
second.)
If you use one timer as a clock event device and the other as a
clocksource, there are no timers left to run the existing
timer_interrupt() handler. So this arrangement would require
GENERIC_CLOCKEVENTS=y, right?
Then, wouldn't all relevant platforms have to support
GENERIC_CLOCKEVENTS=y, if a single binary was to support all of those
platforms?
--
> Yours,
> Linus Walleij
>
next prev parent reply other threads:[~2018-11-20 9:00 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 1:10 [RFC PATCH v2 00/14] m68k: Drop arch_gettimeoffset and adopt clocksource API Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 09/14] m68k: hp300: Remove hp300_gettimeoffset() Finn Thain
2018-11-20 9:09 ` Kars de Jong
2018-11-20 23:13 ` Finn Thain
2018-11-21 8:10 ` Geert Uytterhoeven
2018-11-21 8:41 ` Finn Thain
2018-11-21 8:55 ` Geert Uytterhoeven
2018-11-21 9:47 ` Finn Thain
2018-11-21 10:02 ` Geert Uytterhoeven
2018-11-21 11:14 ` Finn Thain
2018-11-25 1:15 ` Finn Thain
2018-11-25 2:44 ` Michael Schmitz
2018-11-25 3:25 ` Finn Thain
2018-11-21 8:22 ` Kars de Jong
2018-11-19 1:10 ` [RFC PATCH v2 07/14] m68k: atari: Convert to clocksource API Finn Thain
2018-11-19 8:35 ` Michael Schmitz
2018-11-20 8:10 ` Linus Walleij
2018-11-20 8:19 ` Geert Uytterhoeven
2018-11-20 9:30 ` Finn Thain
2018-11-20 9:53 ` Linus Walleij
2018-11-20 10:02 ` Andreas Schwab
2018-11-24 2:03 ` Michael Schmitz
2018-11-24 3:08 ` Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 08/14] m68k: bvme6000: " Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 11/14] m68k: mvme147: " Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 10/14] m68k: mac: " Finn Thain
2018-11-20 8:15 ` Linus Walleij
2018-11-20 9:00 ` Finn Thain [this message]
2018-11-20 9:59 ` Linus Walleij
2018-11-19 1:10 ` [RFC PATCH v2 04/14] m68k: apollo, q40, sun3, sun3x: Remove arch_gettimeoffset implementations Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 01/14] m68k: Call timer_interrupt() with interrupts disabled Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 03/14] m68k: mac: Clean up unused timer definitions Finn Thain
2018-11-20 1:02 ` Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 12/14] m68k: mvme147: Handle timer counter overflow Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 13/14] m68k: mvme16x: Convert to clocksource API Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 02/14] m68k: mac: Fix VIA timer counter accesses Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 06/14] m68k: amiga: Convert to clocksource API Finn Thain
2018-11-20 8:04 ` Linus Walleij
2018-11-19 1:10 ` [RFC PATCH v2 05/14] m68k: Drop ARCH_USES_GETTIMEOFFSET Finn Thain
2018-11-19 1:10 ` [RFC PATCH v2 14/14] m68k: mvme16x: Handle timer counter overflow Finn Thain
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