linux-kernel - Re: [PATCH 1/2] Input: tsc2007 - Disable irq when the irq thread is handling data

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Message-ID: <20111129092208.GA21758@core.coreip.homeip.net>
Date:	Tue, 29 Nov 2011 01:22:08 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Feng Tang <feng.tang@...el.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	kwlee@...kvision.com, joel.clark@...el.com
Subject: Re: [PATCH 1/2] Input: tsc2007 - Disable irq when the irq thread is
 handling data

Hi Feng,

On Tue, Nov 29, 2011 at 04:12:57PM +0800, Feng Tang wrote:
> The TSC2007 data sheet say in some case the HW may fire some false
> interrrupt, which I also met during integrating one TSC2007 device.
> So add the disable_irq/enable_irq protection around data handling.

IRQF_ONESHOT should prevent IRQ from firing again while thread is
servicing it. Did you actually observe it not working?

Thanks.

> 
> Signed-off-by: Feng Tang <feng.tang@...el.com>
> ---
>  drivers/input/touchscreen/tsc2007.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
> index 1f674cb..789f216 100644
> --- a/drivers/input/touchscreen/tsc2007.c
> +++ b/drivers/input/touchscreen/tsc2007.c
> @@ -171,6 +171,13 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
>  	struct ts_event tc;
>  	u32 rt;
>  
> +	/*
> +	 * Disable the irq, as it may fire several other IRQs during
> +	 * this thread is handling data, as suggested by the TSC2007
> +	 * datasheet, p19, "Touch Detect" chapter
> +	 */
> +	disable_irq_nosync(irq);
> +
>  	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
>  
>  		/* pen is down, continue with the measurement */
> @@ -221,6 +228,7 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
>  	if (ts->clear_penirq)
>  		ts->clear_penirq();
>  
> +	enable_irq(irq);
>  	return IRQ_HANDLED;
>  }
>  
> -- 
> 1.7.1
> 
> 

-- 
Dmitry
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