Re: [v2 2/4] platform: (TS-5500) add GPIO support

[H. Peter Anvin]

On 08/30/2011 11:39 AM, Vivien Didelot wrote:
> On Mon, 29 Aug 2011 23:11:33 +0100,
> Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>> On Fri, Aug 26, 2011 at 07:40:25PM -0400, Vivien Didelot wrote:
>>> +	bitno = line_to_bit_map[offset];
>>> +
>>> +	mutex_lock(&drvdata->gpio_lock);
>>> +	byte = inb(ioaddr);
>>> +	mutex_unlock(&drvdata->gpio_lock);
>>
>> Do you really need the lock to do a read?
> 
> Is there any chance for this function to be preempted before reading the
> register, allowing a call to ts5500_gpio_direction_output to occur
> before ts5500_gpio_get is completed?
> 

Wrapping an atomic operation in a mutex makes no sense no matter how you
slice it...
	
	-hpa

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