linux-kernel - Re: [PATCH v1 1/3] gpio: gpio-hisi: Add HiSilicon GPIO support

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Date:   Wed, 9 Dec 2020 10:03:59 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     luojiaxing <luojiaxing@...wei.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v1 1/3] gpio: gpio-hisi: Add HiSilicon GPIO support

Hi Jiaxing,

thanks! waiting for the new patch!

On Wed, Dec 9, 2020 at 9:19 AM luojiaxing <luojiaxing@...wei.com> wrote:

> >> +static void hisi_gpio_irq_disable(struct irq_data *d)
> >> +{
> >> +       struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
> >> +
> >> +       hisi_gpio_irq_set_mask(d);
> >> +       hisi_gpio_write_reg(chip, HISI_GPIO_INTEN_CLR_WX, BIT(irqd_to_hwirq(d)));
> >> +}
> >
> > Interesting with a GPIO hardware that both as enable and mask
> > bits. I can't see why, usually they just have masks but I suppose
> > there is some reason.
>
> I see gpio-dwapb.c distinguishes between enable and mask too.
>
> In my opinion, enable indicates that the user uses the GPIO line as the
> interrupt trigger source,
>
> and mask indicates that the user does not want to see an interrupts for
> a while.
>
> The difference between the two types of flag is that interrupts
> generated during masking are recorded but not lost,
>
> however, if interrupts are disabled, interrupts will lost.

Ah, that makes perfect sense! Thanks for explaining.

Yours,
Linus Walleij