Re: [PATCH v3] gpio/omap: implement irq mask/disable with proper semantic.

[Jon Hunter <jon-hunter@ti.com>]

On 04/22/2013 03:54 AM, Andreas Fenkart wrote:
> When a gpio interrupt is masked, the gpio event will still be latched in
> the interrupt status register so when you unmask it later you may get an
> interrupt straight away. However, if the interrupt is disabled then gpio
> events occurring will not be latched/stored.
> 
> Signed-off-by: Andreas Fenkart <andreas.fenkart@streamunlimited.com>
> ---
>  drivers/gpio/gpio-omap.c |   69 ++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 60 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index 159f5c5..0b66c45 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -772,6 +772,12 @@ static void gpio_ack_irq(struct irq_data *d)
>  	_clear_gpio_irqstatus(bank, gpio);
>  }
>  
> +/**
> + * gpio_mask_irq - mask IRQ signalling
> + * @d : the gpio data we're acting upon
> + *
> + * Only signalling disabled. New IRQ still latched to IRQ status register.
> + */
>  static void gpio_mask_irq(struct irq_data *d)
>  {
>  	struct gpio_bank *bank = irq_data_get_irq_chip_data(d);
> @@ -780,33 +786,76 @@ static void gpio_mask_irq(struct irq_data *d)
>  
>  	spin_lock_irqsave(&bank->lock, flags);
>  	_set_gpio_irqenable(bank, gpio, 0);
> -	_set_gpio_triggering(bank, GPIO_INDEX(bank, gpio), IRQ_TYPE_NONE);

My only concern here is that _set_gpio_triggering() is also handling the
wake-up enable register. So by clearing the triggering here it was also
clearing the wake-up enable. Ideally, I would think that when masking
the interrupt we would also want to disable the wake-up generation too
(if enabled). I think it would only be a problem if someone called
gpio_enable_irq() and the gpio_mask_irq().

Ideally the wake-up enable stuff should be removed from the triggering
function. May be we could add explicit calls to _set_gpio_wakeup().

>  	spin_unlock_irqrestore(&bank->lock, flags);
>  }
>  
> +/**
> + * gpio_unmask_irq - unmask IRQ signalling
> + * @d : the gpio data we're acting upon
> + *
> + * If an IRQ occured while IRQ was masked, you will get an IRQ straight away.
> + */
>  static void gpio_unmask_irq(struct irq_data *d)
>  {
>  	struct gpio_bank *bank = irq_data_get_irq_chip_data(d);
>  	unsigned int gpio = irq_to_gpio(bank, d->irq);
>  	unsigned int irq_mask = GPIO_BIT(bank, gpio);
> -	u32 trigger = irqd_get_trigger_type(d);
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&bank->lock, flags);
> -	if (trigger)
> -		_set_gpio_triggering(bank, GPIO_INDEX(bank, gpio), trigger);
>  
> -	/* For level-triggered GPIOs, the clearing must be done after
> -	 * the HW source is cleared, thus after the handler has run */
> -	if (bank->level_mask & irq_mask) {
> -		_set_gpio_irqenable(bank, gpio, 0);
> +	/*
> +	 * For level-triggered GPIOs, clear the IRQ. If the HW
> +	 * still needs service, IRQ will be latched again
> +	 */
> +	if (bank->level_mask & irq_mask)
>  		_clear_gpio_irqstatus(bank, gpio);
> -	}
>  
>  	_set_gpio_irqenable(bank, gpio, 1);
>  	spin_unlock_irqrestore(&bank->lock, flags);
>  }

Similarly here, can we ensure the wake-up enable is set?

Cheers
Jon