linux-kernel - Re: [PATCH v3 3/5] gpio: gpiolib: Allow free() callback to be overridden

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Date:   Thu, 12 May 2022 12:19:47 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH v3 3/5] gpio: gpiolib: Allow free() callback to be overridden

On Wed, 11 May 2022 19:32:08 +0100,
Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> 
> Allow free() callback to be overridden from irq_domain_ops for
> hierarchical chips.
> 
> This allows drivers to free any resources which are allocated during
> populate_parent_alloc_arg().

Do you mean more than the fwspec? I don't see this being used.

There is also the question of why we need to have dynamic allocation
for the fwspec itself. Why isn't that a simple stack allocation in the
context of gpiochip_hierarchy_irq_domain_alloc()?

	M.

> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/gpio/gpiolib.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index b7694171655c..d36c4a965efc 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1187,15 +1187,18 @@ static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
>  	ops->activate = gpiochip_irq_domain_activate;
>  	ops->deactivate = gpiochip_irq_domain_deactivate;
>  	ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
> -	ops->free = irq_domain_free_irqs_common;
>  
>  	/*
> -	 * We only allow overriding the translate() function for
> +	 * We only allow overriding the translate() and free() functions for
>  	 * hierarchical chips, and this should only be done if the user
> -	 * really need something other than 1:1 translation.
> +	 * really need something other than 1:1 translation for translate()
> +	 * callback and free if user wants to free up any resources which
> +	 * were allocated during callbacks, for example populate_parent_alloc_arg.
>  	 */
>  	if (!ops->translate)
>  		ops->translate = gpiochip_hierarchy_irq_domain_translate;
> +	if (!ops->free)
> +		ops->free = irq_domain_free_irqs_common;
>  }
>  
>  static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
> -- 
> 2.25.1
> 
> 

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