linux-kernel - Re: [PATCH 2/3] gpio: brcmstb: implement irq_mask

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Message-ID: <ad346f69-c2f1-4319-ad59-cadbf2554322@broadcom.com>
Date: Fri, 23 Jan 2026 11:01:37 -0800
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: linux-kernel@...r.kernel.org, Doug Berger <opendmb@...il.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>, Linus Walleij <linusw@...nel.org>,
 Bartosz Golaszewski <brgl@...nel.org>, Christophe Leroy
 <chleroy@...nel.org>, "open list:GPIO SUBSYSTEM"
 <linux-gpio@...r.kernel.org>,
 "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/3] gpio: brcmstb: implement irq_mask_ack

On 1/22/26 11:26, Florian Fainelli wrote:
> 
> 
> On 1/22/2026 11:17 AM, Florian Fainelli wrote:
>>
>>
>> On 1/21/2026 11:36 PM, Andy Shevchenko wrote:
>>> On Thu, Jan 22, 2026 at 3:06 AM Florian Fainelli
>>> <florian.fainelli@...adcom.com> wrote:
>>>>
>>>> From: Doug Berger <opendmb@...il.com>
>>>>
>>>> The irq_mask_ack operation is slightly more efficient than doing
>>>> irq_mask and irq_ack separately.
>>>
>>> I would refer to the callbacks as
>>>
>>> .irq_mask()
>>> .irq_ack()
>>>
>>> et cetera.
>>
>> Ack.
>>
>>>
>>>> More importantly for this driver it bypasses the check of
>>>> irqd_irq_masked ensuring a previously masked but still active
>>>> interrupt gets remasked if unmasked at the hardware level. This
>>>> allows the driver to more efficiently unmask the wake capable
>>>> interrupts when quiescing without needing to enable the irqs
>>>> individually to clear the irqd_irq_masked state.
>>>
>>> ...
>>>
>>>> -// Copyright (C) 2015-2017 Broadcom
>>>> +// Copyright (C) 2015-2026 Broadcom
>>>
>>> Shouldn't it be rather 2015-2017,2026 ? (In one case when I updated a
>>> driver for Intel, I went via Git history to gather the info.)
>>
>> Ack.
>>
>>>
>>> ...
>>>
>>>>   static void brcmstb_gpio_set_imask(struct brcmstb_gpio_bank *bank,
>>>> -               unsigned int hwirq, bool enable)
>>>> +               unsigned int hwirq, bool enable, bool ack)
>>>
>>> This type of interface is usually discouraged as it makes code harder
>>> to read and follow. Since there are a lot of duplication, I recommend
>>> to move the ack op to a separate helper.
>>
>> Good point, knowing the order and what set in those parameters can be 
>> confusing.
>>
>>>
>>> ...
>>>
>>>> -       gpio_generic_write_reg(&bank->chip,
>>>> -                              priv->reg_base + GIO_MASK(bank->id), 
>>>> imask);
>>>> +       if (ack)
>>>> +               gpio_generic_write_reg(&bank->chip,
>>>> +                                      priv->reg_base + 
>>>> GIO_MASK(bank->id),
>>>> +                                      imask);
>>>
>>> Id est this piece...
>>>
>>>
>>>
>>>> +static void brcmstb_gpio_irq_mask_ack(struct irq_data *d)
>>>> +{
>>>> +       struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>>>> +       struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);
>>>> +
>>>> +       brcmstb_gpio_set_imask(bank, d->hwirq, false, true);
>>>
>>> ...and call it here explicitly (seems the only place for it, so it can
>>> even be just moved here without an intermediate helper).
> 
> Actually we need it to be part of brcmsftb_gpio_set_imask() because this 
> is where the guard(gpio_generic_lock_irqsave) resides. I can't really 
> see a better alternative, short of create two implementations: of 
> brcmstb_gpio_set_imask() and brcmstb_gpio_set_imask_ack() which does not 
> feel any better than the proposed patch.

Or creating yet another set of intermediary helpers that are not 
including the locking, and then using them in places where the locking 
needs to be used, yes, that's probably the cleanest, let me do that.
-- 
Florian