From: Jean Delvare <khali@linux-fr.org>
To: Leon Woestenberg <leon.woestenberg@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Mark Brown <broonie@opensource.wolfsonmicro.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sven-Thorsten Dietrich <sven@thebigcorporation.com>,
linux-i2c@vger.kernel.org,
rt-users <linux-rt-users@vger.kernel.org>,
"Ben Dooks (embedded platforms)" <ben-linux@fluff.org>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: yield() in i2c non-happy paths hits BUG under -rt patch
Date: Wed, 18 Nov 2009 17:52:02 +0100 [thread overview]
Message-ID: <20091118175202.490989d8@hyperion.delvare> (raw)
In-Reply-To: <c384c5ea0911180828x7c857189w3316c93bb78100ab@mail.gmail.com>
On Wed, 18 Nov 2009 17:28:53 +0100, Leon Woestenberg wrote:
> On Wed, Nov 18, 2009 at 2:05 AM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > Our timers are very efficient and some day we will need to make jiffies a
> > function and stop the timer ticking for best performance. At that point
> > timers are probably the most efficient way to do much of this.
>
> The problem with I2C bitbanged is the stringent timing, we need a way
> to have fine-grained sleeping
> mixed with real-time tasks in order to make this work.
FWIW, the problem that was initially reported has nothing to do with
this. i2c-algo-bit used mdelay() during transactions, not yield().
yield() is used only in once place, _between_ transactions attempts.
There are no strict timing constraints there.
--
Jean Delvare
next prev parent reply other threads:[~2009-11-18 16:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-07 19:01 yield() in i2c non-happy paths hits BUG under -rt patch Leon Woestenberg
[not found] ` <c384c5ea0911071101u7415d37o2611c542e5fae309-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-11-07 20:01 ` Jean Delvare
[not found] ` <20091107210147.3e754278-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-08 18:57 ` Sven-Thorsten Dietrich
[not found] ` <4AF7148C.9090706-IsH+rWyeNGyzjR9+/8zPv5owlv4uC7bZ@public.gmane.org>
2009-11-12 20:12 ` Jean Delvare
2009-11-13 22:03 ` Thomas Gleixner
2009-11-14 18:02 ` Jean Delvare
[not found] ` <alpine.LFD.2.00.0911132139560.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-16 15:56 ` Mark Brown
[not found] ` <20091116155606.GC29479-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2009-11-18 0:50 ` Leon Woestenberg
2009-11-18 1:05 ` Alan Cox
[not found] ` <20091118010520.4cd397d4-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2009-11-18 16:28 ` Leon Woestenberg
2009-11-18 16:52 ` Jean Delvare [this message]
[not found] ` <20091118175202.490989d8-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-18 20:36 ` Thomas Gleixner
2009-11-19 12:05 ` Jean Delvare
[not found] ` <20091119130526.23a69b85-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-19 12:59 ` Alan Cox
[not found] ` <20091119125906.6ad00edd-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2009-11-19 13:06 ` Peter Zijlstra
2009-11-19 14:00 ` Jean Delvare
2009-11-19 14:15 ` Peter Zijlstra
2009-11-19 13:11 ` Thomas Gleixner
2009-11-19 13:21 ` Peter Zijlstra
2009-11-19 13:22 ` Thomas Gleixner
2009-11-19 13:18 ` Peter Zijlstra
2009-11-18 20:46 ` [PATCH] cleanup sched_yield (sys)call nesting Sven-Thorsten Dietrich
[not found] ` <1258577194.12429.86.camel-ZUMNgey8dAdBci4yedNfAfz91O0DMRRp0E9HWUfgJXw@public.gmane.org>
2009-11-18 20:56 ` Thomas Gleixner
[not found] ` <alpine.LFD.2.00.0911182153010.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-18 21:04 ` Sven-Thorsten Dietrich
2009-11-18 21:34 ` Thomas Gleixner
[not found] ` <alpine.LFD.2.00.0911182233510.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-19 4:48 ` Sven-Thorsten Dietrich
[not found] ` <1258606116.25022.57.camel-ZUMNgey8dAdBci4yedNfAfz91O0DMRRp0E9HWUfgJXw@public.gmane.org>
2009-11-19 10:36 ` Thomas Gleixner
2009-11-19 3:20 ` Ingo Molnar
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