Re: [PATCH v4 2/4] gpio: visconti: Add Toshiba Visconti GPIO support

Hi,

On Wed, Dec 16, 2020 at 09:36:17AM +0000, Marc Zyngier wrote:

On 2020-12-16 09:11, Nobuhiro Iwamatsu wrote:

[...]

quoted

quoted

quoted

+       for (i = 0; i < num_irq; i++) {
+               desc = irq_to_desc(priv->irq[i]);
+               desc->status_use_accessors |= IRQ_NOAUTOEN;
+               if (devm_request_irq(dev, priv->irq[i],
+                                    visconti_gpio_irq_handler, 0, name, priv)) {
+                       dev_err(dev, "failed to request IRQ[%d]\n", i);
+                       return -ENOENT;
+               }
+       }

This should not be needed either when using hiearchical IRQs,
also the irqchip maintainers will beat us up for poking around in the
descs like this.

I understand that the processing equivalent to request_irq() is
processed
by the irqchip frame work (or GIC driver). Is this correct?

request_irq() is reserved to endpoint drivers (the driver for the device
driving the IRQ line). If this is indeed a hierarchical irqchip, the
line allocation will be driven from the GPIO framework, and request_irq()
will perform the activation. There isn't anything that this driver should
do directly other than configuring its own state and passing the request
along to the parent controller.

And yes, mucking with the irq descriptor will get you in massive trouble,
never do that.

I see. Thank you for the explanation.
I got a better understanding.

Best regards,
  Nobuhiro

-- 
Jazz is not dead. It just smells funny...

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