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

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Message-ID: <ba9005ab-f757-4018-96ed-a10bcef08165@broadcom.com>
Date: Thu, 22 Jan 2026 11:26:47 -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 1/22/2026 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.
--
Florian