Re: [PATCH v3 1/5] drivers: pinctrl: qcom: add wakeup capability to GPIO

[Lina Iyer]

On Fri, Sep 21 2018 at 17:11 -0600, Marc Zyngier wrote:
> Hi Lina,
>
> On Tue, 04 Sep 2018 22:18:06 +0100,
> Lina Iyer <ilina@xxxxxxxxxxxxxx> wrote:
[...]
> > +static irqreturn_t wake_irq_gpio_handler(int irq, void *data)
> > +{
> > +	struct irq_data *irqd = data;
> > +	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
> > +	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> > +	const struct msm_pingroup *g;
> > +	unsigned long flags;
> > +	u32 val;
> > +
> > +	if (!irqd_is_level_type(irqd)) {
> > +		g = &pctrl->soc->groups[irqd->hwirq];
> > +		raw_spin_lock_irqsave(&pctrl->lock, flags);
> > +		val = BIT(g->intr_status_bit);
> > +		writel(val, pctrl->regs + g->intr_status_reg);
>
> write_relaxed, please.
>
> > +		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> > +	}
>
> Overall, this requires some form of documentation (I'll have forgotten
> about the whole thing quickly enough).
Sure, I will address them both.
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int msm_gpio_pdc_pin_request(struct irq_data *d)
> > +{
> > +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> > +	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> > +	struct platform_device *pdev = to_platform_device(pctrl->dev);
> > +	const char *pin_name;
> > +	int irq;
> > +	int ret;
> > +
> > +	pin_name = kasprintf(GFP_KERNEL, "gpio%lu", d->hwirq);
> > +	if (!pin_name)
> > +		return -ENOMEM;
> > +
> > +	irq = platform_get_irq_byname(pdev, pin_name);
> > +	if (irq < 0) {
> > +		kfree(pin_name);
> > +		return 0;
> > +	}
> > +
> > +	ret = request_irq(irq, wake_irq_gpio_handler, irqd_get_trigger_type(d),
> > +			  pin_name, d);
> > +	if (ret) {
> > +		pr_warn("GPIO-%lu could not be set up as wakeup", d->hwirq);
>
> This message doesn't correspond to what you're doing here.
Well, I thought the message is most relevant because, we will not be
able to wake up from this GPIO IRQ. But, I will change it.

> > +		kfree(pin_name);
> > +		return ret;
> > +	}
> > +
> > +	irq_set_handler_data(d->irq, irq_get_irq_data(irq));
> > +	disable_irq(irq);
>
> Who enables this interrupt?
Suspend/resume code does the swap of enable/disable of PDC IRQ vs GPIO
IRQ in patch #4.

> There is a gap between request_irq and disable_irq, where you can take
> the interrupt, and not having set the handler data. Horrible things
> will happen in this situation.
>
> A slightly better way of doing that would be:
>
> 	// Prevent the interrupt from being enabled on request
> 	irq_set_status_flags(d->irq, IRQ_NOAUTOEN);
> 	ret = request_irq(...);
> 	irq_set_handler(...);
>
> and let the enable_irq() do its thing when it happens (where?).
Oh. This is better. Will amend.

Thanks for the review.

-- Lina

> > +
> > +	return 0;
> > +}
> > +
> > +static int msm_gpio_pdc_pin_release(struct irq_data *d)
> > +{
> > +	struct irq_data *pdc_irqd = irq_get_handler_data(d->irq);
> > +	const void *name;
> > +
> > +	if (pdc_irqd) {
> > +		irq_set_handler_data(d->irq, NULL);
> > +		name = free_irq(pdc_irqd->irq, d);
> > +		kfree(name);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int msm_gpio_irq_reqres(struct irq_data *d)
> > +{
> > +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> > +
> > +	if (gpiochip_lock_as_irq(gc, irqd_to_hwirq(d))) {
> > +		dev_err(gc->parent, "unable to lock HW IRQ %lu for IRQ\n",
> > +			irqd_to_hwirq(d));
> > +		return -EINVAL;
> > +	}
> > +
> > +	return msm_gpio_pdc_pin_request(d);
> > +}
> > +
> > +static void msm_gpio_irq_relres(struct irq_data *d)
> > +{
> > +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> > +
> > +	msm_gpio_pdc_pin_release(d);
> > +	gpiochip_unlock_as_irq(gc, irqd_to_hwirq(d));
> > +}
> > +
> >  static int msm_gpio_init(struct msm_pinctrl *pctrl)
> >  {
> >  	struct gpio_chip *chip;
> > @@ -887,6 +983,8 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
> >  	pctrl->irq_chip.irq_ack = msm_gpio_irq_ack;
> >  	pctrl->irq_chip.irq_set_type = msm_gpio_irq_set_type;
> >  	pctrl->irq_chip.irq_set_wake = msm_gpio_irq_set_wake;
> > +	pctrl->irq_chip.irq_request_resources = msm_gpio_irq_reqres;
> > +	pctrl->irq_chip.irq_release_resources = msm_gpio_irq_relres;
> >
> >  	ret = gpiochip_add_data(&pctrl->chip, pctrl);
> >  	if (ret) {
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project
>
> Thanks,
>
> 	M.
>
> --
> Jazz is not dead, it just smell funny.