Re: [PATCH v3 1/1] gpio: mpfs: add polarfire soc gpio support

[Marc Zyngier <maz@kernel.org>]

On Sat, 16 Jul 2022 08:11:13 +0100,
<lewis.hanly@microchip.com> wrote:
> 
> From: Lewis Hanly <lewis.hanly@microchip.com>
> 
> Add a driver to support the Polarfire SoC gpio controller.
> 
> Signed-off-by: Lewis Hanly <lewis.hanly@microchip.com>

[...]

> +static int mpfs_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
> +					   unsigned int child,
> +					   unsigned int child_type,
> +					   unsigned int *parent,
> +					   unsigned int *parent_type)
> +{
> +	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> +	struct irq_data *d = irq_get_irq_data(mpfs_gpio->irq_number[child]);

This looks totally wrong. It means that you have already instantiated
part of the hierarchy, and it is likely that you will get multiple
hierarchy sharing some levels, which isn't intended.

> +	*parent_type = IRQ_TYPE_NONE;
> +	*parent = irqd_to_hwirq(d);
> +
> +	return 0;
> +}
> +
> +static int mpfs_gpio_probe(struct platform_device *pdev)
> +{
> +	struct clk *clk;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = pdev->dev.of_node;
> +	struct device_node *irq_parent;
> +	struct gpio_irq_chip *girq;
> +	struct irq_domain *parent;
> +	struct mpfs_gpio_chip *mpfs_gpio;
> +	int i, ret, ngpio;
> +
> +	mpfs_gpio = devm_kzalloc(dev, sizeof(*mpfs_gpio), GFP_KERNEL);
> +	if (!mpfs_gpio)
> +		return -ENOMEM;
> +
> +	mpfs_gpio->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(mpfs_gpio->base))
> +		return dev_err_probe(dev, PTR_ERR(mpfs_gpio->clk), "input clock not found.\n");
> +
> +	clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(clk))
> +		return dev_err_probe(dev, PTR_ERR(clk), "devm_clk_get failed\n");
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to enable clock\n");
> +
> +	mpfs_gpio->clk = clk;
> +
> +	ngpio = of_irq_count(node);
> +	if (ngpio > NUM_GPIO) {
> +		ret = -ENXIO;
> +		goto cleanup_clock;
> +	}
> +
> +	irq_parent = of_irq_find_parent(node);
> +	if (!irq_parent) {
> +		ret = -ENODEV;
> +		goto cleanup_clock;
> +	}
> +	parent = irq_find_host(irq_parent);
> +	if (!parent) {
> +		ret = -ENODEV;
> +		goto cleanup_clock;
> +	}
> +
> +	/* Get the interrupt numbers. */
> +	/* Clear/Disable All interrupts before enabling parent interrupts. */
> +	for (i = 0; i < ngpio; i++) {
> +		mpfs_gpio->irq_number[i] = platform_get_irq(pdev, i);

Bingo. You are allocating the interrupt for the level below. You
really shouldn't do that.

If you need to retrieve the *hwirq* for the level below, you need to
parse the DT without triggering an IRQ allocation (of_irq_parse_one()
and co).

	M.

-- 
Without deviation from the norm, progress is not possible.

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