From: John Stultz <john.stultz@linaro.org>
To: Baruch Siach <baruch@tkos.co.il>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jamie Iles <jamie@jamieiles.com>,
Dinh Nguyen <dinguyen@altera.com>
Subject: Re: [RFC PATCH 2/2] clocksource: dw_apb: allow build for architectures other than arm
Date: Thu, 30 May 2013 09:11:17 -0700 [thread overview]
Message-ID: <51A77A25.8080306@linaro.org> (raw)
In-Reply-To: <20130530053233.GL25186@sapphire.tkos.co.il>
On 05/29/2013 10:32 PM, Baruch Siach wrote:
> Hi John,
>
> On Tue, May 28, 2013 at 01:24:17PM -0700, John Stultz wrote:
>> On 05/26/2013 05:12 AM, Baruch Siach wrote:
>>> static const struct of_device_id osctimer_ids[] __initconst = {
>>> @@ -124,3 +135,10 @@ void __init dw_apb_timer_init(void)
>>> init_sched_clock();
>>> }
>>> +
>>> +#ifndef CONFIG_HAVE_SETUP_SCHED_CLOCK
>>> +unsigned long long notrace sched_clock()
>>> +{
>>> + return read_sched_clock() * sched_clock_mult;
>>> +}
>>> +#endif
>> Also, can you try to condense the number of #ifndef
>> CONFIG_HAVE_SETUP_SCHED_CLOCK checks to one, and consolidate the
>> needed functions all in that one conditional?
> Thanks for your comments. I'll rework the patch and resubmit.
>
> I've just noticed that I have a bigger problem. read_sched_clock() returns
> u32, not u64. This means that in a rate of, say, 100MHz it will wrap around
> after a little more than 40 seconds. Would it make sense to put ARM's 32 bin
> sched_clock extension code (arch/arm/kernel/sched_clock.c) is a common place
> (maybe drivers/clocksource), and use that? There seems to be nothing ARM
> specific in this code, after all.
Yea, working out an actual generic sched_clock implementation is
something I'd like to see done.
Though I'd really rather we not toss yet another chunk of infrastructure
in the drivers/clocksource directory. Instead we should probably have a
kernel/time/sched_clock.c.
Then its just the issue of tying that and the clocksource code together
so you just register existing capable clocksources with a SCHED_CLOCK
flag or via a different registration hook.
I don't think it will be an easy job, but if you want to give it a shot,
I'd be quite interested in reviewing the patches!
thanks
-john
next prev parent reply other threads:[~2013-05-30 16:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-26 12:12 [RFC PATCH 2/2] clocksource: dw_apb: allow build for architectures other than arm Baruch Siach
2013-05-28 20:24 ` John Stultz
2013-05-30 5:32 ` Baruch Siach
2013-05-30 16:11 ` John Stultz [this message]
2013-05-31 5:32 ` Baruch Siach
2013-06-20 14:44 ` Pavel Machek
2013-06-20 15:03 ` Baruch Siach
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=51A77A25.8080306@linaro.org \
--to=john.stultz@linaro.org \
--cc=baruch@tkos.co.il \
--cc=dinguyen@altera.com \
--cc=jamie@jamieiles.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).