linux-kernel - Re: [PATCH v6 4/5] mfd: tqmx86: make IRQ setup errors non-fatal

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Message-ID: <20241106090027.GI1807686@google.com>
Date: Wed, 6 Nov 2024 09:00:27 +0000
From: Lee Jones <lee@...nel.org>
To: Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc: linux@...tq-group.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/5] mfd: tqmx86: make IRQ setup errors non-fatal

On Mon, 04 Nov 2024, Matthias Schiffer wrote:

> GPIO IRQ setup can fail either because an invalid IRQ was passed as a
> parameter, or because the GPIO controller does not support interrupts.
> Neither is severe enough to stop the whole probe; simply disable IRQ
> support in the GPIO resource when setup fails.
> 
> The code is made a bit more robust by introduing a define for the index
> of the IRQ resource in the resource list instead of assuming that it is
> at index 0.
> 
> Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
> ---
> 
> v2: no changes (was patch 3/4)
> v3: replace IRQ 0 resource with an empty placeholder to simplify error handling
> v4: no changes
> v5: move placeholder to the end of the resource array, use define for index
> v6: no changes
> 
>  drivers/mfd/tqmx86.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mfd/tqmx86.c b/drivers/mfd/tqmx86.c
> index 8aa448a67c9a5..1fd2212bf492c 100644
> --- a/drivers/mfd/tqmx86.c
> +++ b/drivers/mfd/tqmx86.c
> @@ -60,6 +60,9 @@ static uint gpio_irq;
>  module_param(gpio_irq, uint, 0);
>  MODULE_PARM_DESC(gpio_irq, "GPIO IRQ number (valid parameters: 7, 9, 12)");
>  
> +/* Index of IRQ placeholder in resource list */
> +#define TQMX86_IRQ_GPIO 1
> +
>  static const struct resource tqmx_i2c_soft_resources[] = {
>  	DEFINE_RES_IO(TQMX86_IOBASE_I2C, TQMX86_IOSIZE_I2C),
>  };
> @@ -68,13 +71,10 @@ static const struct resource tqmx_watchdog_resources[] = {
>  	DEFINE_RES_IO(TQMX86_IOBASE_WATCHDOG, TQMX86_IOSIZE_WATCHDOG),
>  };
>  
> -/*
> - * The IRQ resource must be first, since it is updated with the
> - * configured IRQ in the probe function.
> - */
>  static struct resource tqmx_gpio_resources[] = {
> -	DEFINE_RES_IRQ(0),
>  	DEFINE_RES_IO(TQMX86_IOBASE_GPIO, TQMX86_IOSIZE_GPIO),
> +	/* Placeholder for IRQ resource - filled in by the probe function */

Drop the " - filled in ..." part.  This is a common practice.

> +	[TQMX86_IRQ_GPIO] = {},

Not quite.  What happens if someone comes along and inserts a resource
above this one?  You need to index all of them.  Use an enum.

>  };
>  
>  static struct i2c_board_info tqmx86_i2c_devices[] = {
> @@ -255,13 +255,8 @@ static int tqmx86_probe(struct platform_device *pdev)
>  	if (gpio_irq) {
>  		err = tqmx86_setup_irq(dev, "GPIO", gpio_irq, io_base,
>  				       TQMX86_REG_IO_EXT_INT_GPIO_SHIFT);
> -		if (err)
> -			return err;
> -
> -		/* Assumes the IRQ resource is first. */
> -		tqmx_gpio_resources[0].start = gpio_irq;
> -	} else {
> -		tqmx_gpio_resources[0].flags = 0;
> +		if (!err)
> +			tqmx_gpio_resources[TQMX86_IRQ_GPIO] = DEFINE_RES_IRQ(gpio_irq);

This section just became a lot nicer.

>  	}
>  
>  	ocores_platform_data.clock_khz = tqmx86_board_id_to_clk_rate(dev, board_id);
> -- 
> TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany
> Amtsgericht München, HRB 105018
> Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider
> https://www.tq-group.com/
> 

-- 
Lee Jones [李琼斯]