linux-kernel - Re: [PATCH v8 07/14] gpio: thunderx: Use the default parent apis for {request,release}

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Date:   Tue, 10 Mar 2020 16:27:31 -0700
From:   Tim Harvey <tharvey@...eworks.com>
To:     Lokesh Vutla <lokeshvutla@...com>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, Nishanth Menon <nm@...com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>,
        Tero Kristo <t-kristo@...com>, Sekhar Nori <nsekhar@...com>,
        Tony Lindgren <tony@...mide.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Device Tree Mailing List <devicetree@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v8 07/14] gpio: thunderx: Use the default parent apis for {request,release}_resources

On Tue, Apr 30, 2019 at 3:14 AM Lokesh Vutla <lokeshvutla@...com> wrote:
>
> thunderx_gpio_irq_{request,release}_resources apis are trying to
> {request,release} resources on parent interrupt. There are default
> apis doing the same. Use the default parent apis instead of writing
> the same code snippet.
>
> Cc: linux-gpio@...r.kernel.org
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Acked-by: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
> ---
> Changes since v7:
> - None
>
>  drivers/gpio/gpio-thunderx.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpio/gpio-thunderx.c b/drivers/gpio/gpio-thunderx.c
> index 1306722faa5a..715371b5102a 100644
> --- a/drivers/gpio/gpio-thunderx.c
> +++ b/drivers/gpio/gpio-thunderx.c
> @@ -363,22 +363,16 @@ 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;
>
> -       if (parent_data && parent_data->chip->irq_request_resources) {
> -               r = parent_data->chip->irq_request_resources(parent_data);
> -               if (r)
> -                       goto error;
> -       }
> +       r = irq_chip_request_resources_parent(data);
> +       if (r)
> +               gpiochip_unlock_as_irq(&txgpio->chip, txline->line);

Lokesh,

This patch breaks irq resources for thunderx-gpio as
parent_data->chip->irq_request_resources is undefined thus your new
irq_chip_request_resources_parent() returns -ENOSYS causing this
function to return an error where as before it would happily return 0.

Is the following the correct fix or should we qualify
data->parent_data->chip->irq_request_resources before calling
irq_chip_request_resources_parent() in thunderx-gpio?

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b3fa2d8..b2435ecb 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1525,7 +1525,7 @@ int irq_chip_request_resources_parent(struct
irq_data *data)
        if (data->chip->irq_request_resources)
                return data->chip->irq_request_resources(data);

-       return -ENOSYS;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(irq_chip_request_resources_parent);

Regards,

Tim