Re: [PATCH] mfd: add MAX8907 core driver

[Stephen Warren <swarren@wwwdotorg.org>]

On 07/26/2012 02:35 PM, Mark Brown wrote:
> On Thu, Jul 26, 2012 at 01:40:30PM -0600, Stephen Warren wrote:

>> +		if (!irqd_irq_disabled(d) && (value & irq_data->offs)) {
> 
> This looks very suspicious...  why do we need to call 
> irqd_irq_disabled() here?

I believe the status register reflects the unmasked status, it's just
the interrupt signal that's affected by the mask.

>> +static void max8907_irq_enable(struct irq_data *data) +{ +	/*
>> Everything happens in max8907_irq_sync_unlock */ +}
> 
>> +static void max8907_irq_disable(struct irq_data *data) +{ +	/*
>> Everything happens in max8907_irq_sync_unlock */ +}
> 
> The fact that these functions are empty is the second part of the
> above suspicous check for disabled IRQs.  We're just completely
> ignoring the caller here.  What would idiomatically happen is that
> we'd update a variable here then write it out in the unmask.
> 
> If these functions really should be empty then they should be
> omitted.
> 
>> +static int max8907_irq_set_wake(struct irq_data *data, unsigned
>> int on) +{ +	/* Everything happens in max8907_irq_sync_unlock */ 
>> + +	return 0; +}
> 
> Again, this doesn't look clever at all.

So the idea here was that the IRQ core is already maintaining state
which describes which IRQs are enabled/disabled and wake/not. Rather
than have irq_enable/irq_disable/set_wake do nothing but save the same
state to irq_chip-specific structures, I removed the body of those
functions and instead just call irqd_irq_disabled() etc. wherever I
would have accessed the "local" state. Is that not a legitimate design
then?