linux-kernel - Re: [PATCH] of/platform: Fix no irq domain found errors when populating interrupts

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Message-Id: <20131124213651.59750C402C3@trevor.secretlab.ca>
Date:	Sun, 24 Nov 2013 21:36:51 +0000
From:	Grant Likely <grant.likely@...aro.org>
To:	Tony Lindgren <tony@...mide.com>,
	Rob Herring <rob.herring@...xeda.com>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] of/platform: Fix no irq domain found errors when populating interrupts

On Fri, 22 Nov 2013 16:43:35 -0800, Tony Lindgren <tony@...mide.com> wrote:
> Currently we get the following kind of errors if we try to use
> interrupt phandles to irqchips that have not yet initialized:
> 
> irq: no irq domain found for /ocp/pinmux@...02030 !
> WARNING: CPU: 0 PID: 1 at drivers/of/platform.c:171 of_device_alloc+0x144/0x184()
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.0-00038-g42a9708 #1012
> (show_stack+0x14/0x1c)
> (dump_stack+0x6c/0xa0)
> (warn_slowpath_common+0x64/0x84)
> (warn_slowpath_null+0x1c/0x24)
> (of_device_alloc+0x144/0x184)
> (of_platform_device_create_pdata+0x44/0x9c)
> (of_platform_bus_create+0xd0/0x170)
> (of_platform_bus_create+0x12c/0x170)
> (of_platform_populate+0x60/0x98)
> ...
> 
> This is because we're wrongly trying to populate resources that are not
> yet available. It's perfectly valid to create irqchips dynamically,
> so let's fix up the issue by populating the interrupt resources based
> on a notifier call instead.
> 
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> 
> ---
> 
> Rob & Grant, care to merge this for the -rc if this looks OK to you?
> 
> These happen for example when using interrupts-extended for omap
> wake-up interrupts where the irq domain is created by pinctrl-single.c
> at module_init time.
> 
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -130,6 +130,56 @@ void of_device_make_bus_id(struct device *dev)
>  	dev_set_name(dev, "%s.%d", node->name, magic - 1);
>  }
>  
> +/*
> + * The device interrupts are not necessarily available for all
> + * irqdomains initially so we need to populate them using a
> + * notifier.
> + */
> +static int of_device_resource_notify(struct notifier_block *nb,
> +				     unsigned long event, void *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct device_node *np = pdev->dev.of_node;
> +	struct resource *res = pdev->resource;
> +	struct resource *irqr = NULL;
> +	int num_irq, i, found = 0;
> +
> +	if (event != BUS_NOTIFY_BIND_DRIVER)
> +		return 0;
> +
> +	if (!np)
> +		goto out;
> +
> +	num_irq = of_irq_count(np);
> +	if (!num_irq)
> +		goto out;
> +
> +	for (i = 0; i < pdev->num_resources; i++, res++) {
> +		if (res->flags != IORESOURCE_IRQ ||
> +		    res->start != -EPROBE_DEFER ||
> +		    res->end != -EPROBE_DEFER)
> +			continue;
> +
> +		if (!irqr)
> +			irqr = res;
> +		found++;
> +	}
> +
> +	if (!found)
> +		goto out;
> +
> +	if (found != num_irq) {
> +		dev_WARN(dev, "error populating irq resources: %i != %i\n",
> +			 found, num_irq);
> +		goto out;
> +	}
> +
> +	WARN_ON(of_irq_to_resource_table(np, irqr, num_irq) != num_irq);
> +
> +out:
> +	return NOTIFY_DONE;
> +}
> +
>  /**
>   * of_device_alloc - Allocate and initialize an of_device
>   * @np: device node to assign to device
> @@ -168,7 +218,13 @@ struct platform_device *of_device_alloc(struct device_node *np,
>  			rc = of_address_to_resource(np, i, res);
>  			WARN_ON(rc);
>  		}
> -		WARN_ON(of_irq_to_resource_table(np, res, num_irq) != num_irq);
> +
> +		/* See of_device_resource_notify for populating interrupts */
> +		for (i = 0; i < num_irq; i++, res++) {
> +			res->flags = IORESOURCE_IRQ;
> +			res->start = -EPROBE_DEFER;
> +			res->end = -EPROBE_DEFER;
> +		}

I actually like the idea of completely allocating the resource structure
but leaving some entries empty. However, I agree with rmk that putting
garbage into a resource structure is a bad idea. What about changing the
value of flags to 0 or some other value to be obviously an empty
property and give the follow up parsing some context about which ones it
needs to attempt to recalculate?

However, I still don't like the notifier approach of actually triggering
the fixup. We need something better.

g.

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