linux-kernel - Re: [PATCH] mfd: speedup twl4030 irq response time and decrease irq disable time

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Date:	Tue, 28 Sep 2010 13:01:32 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>, linux-omap@...r.kernel.org,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Balaji T K <balajitk@...com>, Rajendra Nayak <rnayak@...com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH] mfd: speedup twl4030 irq response time and decrease irq
 disable time

CC genirq guys

2010/9/28 Mark Brown <broonie@...nsource.wolfsonmicro.com>:
> On Tue, Sep 28, 2010 at 08:25:24AM +0800, Ming Lei wrote:
>> 2010/9/27 Samuel Ortiz <sameo@...ux.intel.com>:
>
>> > Wouldn't converting your twl4030_irq_thread() to the threaded IRQ framework
>> > fix that problem ?
>
>> IRQ_DISABLED flag is set by disable_irq_nosync called from PIH handler,
>> then thread function can't be executed in irq thread function, so we can't
>> convert this to threaded IRQ framework simply.
>
> Have you raised this issue with the genirq guys?  This sounds like
> something that the core infrastructure should be able to cope with.
>

Even genirq guys can help us to convert to irq thread framework, I
don't think there is good way to set priority for one irq thread.

For twl4030, if we can make twl4030_irq_thread to run at higher
priority than that of other irq thread, the PIH irq disable time can be
decreased further since other irq thread waken up by twl4030_irq_thread
can preempt the running of twl4030_irq_thread, and the PIH irq will be
enabled until complete of twl4030_irq_thread.

thanks,
-- 
Lei Ming
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