linux-kernel - Re: [PATCH] gpio: thunderx: fix irq_request

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Date:   Fri, 13 Mar 2020 16:31:52 +0100
From:   Robert Richter <rrichter@...vell.com>
To:     Tim Harvey <tharvey@...eworks.com>
CC:     Linus Walleij <linus.walleij@...aro.org>,
        Lokesh Vutla <lokeshvutla@...com>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpio: thunderx: fix irq_request_resources

On 11.03.20 08:43:53, Tim Harvey wrote:
> If there are no parent resources do not call irq_chip_request_resources_parent
> at all as this will return an error.
> 
> This resolves a regression where devices using a thunderx gpio as an interrupt
> would fail probing.
> 
> Fixes: 0d04d0c ("gpio: thunderx: Use the default parent apis for {request,release}_resources")
> Signed-off-by: Tim Harvey <tharvey@...eworks.com>
> ---
>  drivers/gpio/gpio-thunderx.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-thunderx.c b/drivers/gpio/gpio-thunderx.c
> index 4627704..f84b9b1 100644
> --- a/drivers/gpio/gpio-thunderx.c
> +++ b/drivers/gpio/gpio-thunderx.c
> @@ -366,15 +366,18 @@ static int thunderx_gpio_irq_request_resources(struct irq_data *data)
>  {
>  	struct thunderx_line *txline = irq_data_get_irq_chip_data(data);
>  	struct thunderx_gpio *txgpio = txline->txgpio;
> +	struct irq_data *parent_data = data->parent_data;
>  	int r;
>  
>  	r = gpiochip_lock_as_irq(&txgpio->chip, txline->line);
>  	if (r)
>  		return r;
>  
> -	r = irq_chip_request_resources_parent(data);
> -	if (r)
> -		gpiochip_unlock_as_irq(&txgpio->chip, txline->line);
> +	if (parent_data && parent_data->chip->irq_request_resources) {
> +		r = irq_chip_request_resources_parent(data);
> +		if (r)
> +			gpiochip_unlock_as_irq(&txgpio->chip, txline->line);
> +	}

There is no unlocking for the else case. I would assume the
parent_data should be checked before grabbing the lock, or is this
intended?

-Robert

>  
>  	return r;
>  }
> -- 
> 2.7.4
>