linux-kernel - Re: [PATCH 1/2] tsc2007: remove HR timer

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Message-ID: <20090714082128.GF2822@dtor-d630.eng.vmware.com>
Date:	Tue, 14 Jul 2009 01:21:28 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Richard Röjfors 
	<richard.rojfors.ext@...ean-labs.com>
Cc:	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-input@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	kwangwoo.lee@...il.com, Trilok Soni <soni.trilok@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] tsc2007: remove HR timer

On Tue, Jul 14, 2009 at 10:00:06AM +0200, Richard Röjfors wrote:
> On 7/14/09 9:08 AM, Thierry Reding wrote:
>> * Dmitry Torokhov wrote:
>>> Hi Richard,
>>>
>>> On Tue, Jun 23, 2009 at 01:54:48PM +0200, Richard Röjfors wrote:
>> [...]
>>> +static void tsc2007_free_irq(struct tsc2007 *ts)
>>> +{
>>> +	free_irq(ts->irq, ts);
>>> +	if (cancel_delayed_work_sync(&ts->work)) {
>>> +		/*
>>> +		 * Work was pending, therefore we need to enable
>>> +		 * IRQ here to balance the disable_irq() done in the
>>> +		 * interrupt handler.
>>> +		 */
>>> +		enable_irq(ts->irq);
>>> +	}
>>> +}
>> [...]
>>> -static int tsc2007_remove(struct i2c_client *client)
>>> +static int __devexit tsc2007_remove(struct i2c_client *client)
>>>   {
>>>   	struct tsc2007	*ts = i2c_get_clientdata(client);
>>> -	struct tsc2007_platform_data *pdata;
>>> +	struct tsc2007_platform_data *pdata = client->dev.platform_data;
>>>
>>> -	cancel_delayed_work_sync(&ts->work);
>>> +	free_irq(ts->irq, ts);
>>> +	if (cancel_delayed_work_sync(&ts->work)) {
>>> +		/*
>>> +		 * Work was pending, therefore we need to enable
>>> +		 * IRQ here to balance the disabel done in the
>>> +		 * interrupt handler.
>>> +		 */
>>> +		enable_irq(ts->irq);
>>> +	}
>>
>> Shouldn't this be tsc2007_free_irq(ts) as well?
>
> Is this really good enough? The work function might re-enable the IRQ.

I am pretty sure it is. cancel_delayed_work_sync() will terurn true if
there was work scheduled but not yet executed. In this case we know that
IRQ was disabled by interrupt handler and will re-enable it.

-- 
Dmitry
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