Re: [PATCH v2 4/4] amba: Properly handle device probe without IRQ domain

[Rob Herring <robh@kernel.org>]

On Fri, Aug 27, 2021 at 11:06:00PM +0800, Kefeng Wang wrote:
> of_amba_device_create() uses irq_of_parse_and_map() to translate
> a DT interrupt specification into a Linux virtual interrupt number.
> 
> But it doesn't properly handle the case where the interrupt controller
> is not yet available, eg, when pl011 interrupt is connected to MBIGEN
> interrupt controller, because the mbigen initialization is too late,
> which will lead to no IRQ due to no IRQ domain found, log is shown below,
>   "irq: no irq domain found for uart0 !"
> 
> use of_irq_get() to return -EPROBE_DEFER as above, and in the driver
> deferred probe, it will properly handle in such case, also return 0
> in other fail cases to be consistent as before.
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Reported-by: Ruizhe Lin <linruizhe@huawei.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  drivers/amba/bus.c    | 27 +++++++++++++++++++++++++++
>  drivers/of/platform.c |  6 +-----
>  2 files changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 4d3a565ca079..96e84ce66e9a 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -19,6 +19,7 @@
>  #include <linux/clk/clk-conf.h>
>  #include <linux/platform_device.h>
>  #include <linux/reset.h>
> +#include <linux/of_irq.h>
>  
>  #define to_amba_driver(d)	container_of(d, struct amba_driver, drv)
>  
> @@ -170,6 +171,28 @@ static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
>  	return retval;
>  }
>  
> +static int of_amba_device_decode_irq(struct amba_device *dev)
> +{
> +	struct device_node *node = dev->dev.of_node;
> +	int i, irq;
> +
> +	if (IS_ENABLED(CONFIG_OF_IRQ) && node) {

I don't think this check is needed. If either is false, we should return 
an errno from of_irq_get().

> +		/* Decode the IRQs and address ranges */
> +		for (i = 0; i < AMBA_NR_IRQS; i++) {
> +			irq = of_irq_get(node, i);
> +			if (irq < 0) {
> +				if (irq == -EPROBE_DEFER)
> +					return irq;
> +				irq = 0;
> +			}
> +
> +			dev->irq[i] = irq;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * These are the device model conversion veneers; they convert the
>   * device model structures to our more specific structures.
> @@ -182,6 +205,10 @@ static int amba_probe(struct device *dev)
>  	int ret;
>  
>  	do {
> +		ret = of_amba_device_decode_irq(pcdev);
> +		if (ret)
> +			break;
> +
>  		ret = of_clk_set_defaults(dev->of_node, false);
>  		if (ret < 0)
>  			break;
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 74afbb7a4f5e..32d5ff8df747 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -222,7 +222,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  {
>  	struct amba_device *dev;
>  	const void *prop;
> -	int i, ret;
> +	int ret;
>  
>  	pr_debug("Creating amba device %pOF\n", node);
>  
> @@ -253,10 +253,6 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  	if (prop)
>  		dev->periphid = of_read_ulong(prop, 1);
>  
> -	/* Decode the IRQs and address ranges */
> -	for (i = 0; i < AMBA_NR_IRQS; i++)
> -		dev->irq[i] = irq_of_parse_and_map(node, i);
> -
>  	ret = of_address_to_resource(node, 0, &dev->res);
>  	if (ret) {
>  		pr_err("amba: of_address_to_resource() failed (%d) for %pOF\n",
> -- 
> 2.18.0.huawei.25
> 
>