linux-kernel - Re: [PATCH V4 3/5] gpio: gpio-xilinx: Add interrupt support

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Date:   Thu, 7 Jan 2021 10:26:48 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Srinivas Neeli <srinivas.neeli@...inx.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Michal Simek <michal.simek@...inx.com>,
        Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
        sgoud@...inx.com, Robert Hancock <hancock@...systems.ca>,
        William Breathitt Gray <vilhelm.gray@...il.com>,
        Syed Nayyar Waris <syednwaris@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        git@...inx.com
Subject: Re: [PATCH V4 3/5] gpio: gpio-xilinx: Add interrupt support

On Wed, Jan 6, 2021 at 1:27 PM Srinivas Neeli <srinivas.neeli@...inx.com> wrote:

> Adds interrupt support to the Xilinx GPIO driver so that rising and
> falling edge line events can be supported. Since interrupt support is
> an optional feature in the Xilinx IP, the driver continues to support
> devices which have no interrupt provided.
> Depends on OF_GPIO framework for of_xlate function to translate
> gpiospec to the GPIO number and flags.
>
> Signed-off-by: Robert Hancock <hancock@...systems.ca>
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
> Signed-off-by: Srinivas Neeli <srinivas.neeli@...inx.com>
(...)

>  config GPIO_XILINX
>         tristate "Xilinx GPIO support"
> +       select GPIOLIB_IRQCHIP
> +       select IRQ_DOMAIN_HIERARCHY

Why do you select IRQ_DOMAIN_HIERARCHY?

You don't seem to use it.

> +#include <linux/of_gpio.h>

No modern driver should include this header. I suspect you
can just drop it.

See drivers/gpio/TODO

> +       /* Update cells with gpio-cells value */
> +       if (of_property_read_u32(np, "#gpio-cells", &cells))
> +               dev_dbg(&pdev->dev, "Missing gpio-cells property\n");
> +
>         /*
>          * Check device node and parent device node for device width
>          * and assume default width of 32
> @@ -343,6 +545,7 @@ static int xgpio_probe(struct platform_device *pdev)
>         chip->gc.parent = &pdev->dev;
>         chip->gc.direction_input = xgpio_dir_in;
>         chip->gc.direction_output = xgpio_dir_out;
> +       chip->gc.of_gpio_n_cells = cells;

This looks a bit dangerous. What actually happens if this is something
like 3. The translate function is not going to work. I would just dev_err()
and bail out if #gpio-cells != 2.

Other than that this looks good!

Yours,
Linus Walleij