linux-kernel - Re: [PATCH 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

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Message-ID: <e08c9f6e-0e84-5f2a-766d-7a1c45bd977a@codeaurora.org>
Date:   Sat, 23 May 2020 22:36:51 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     bjorn.andersson@...aro.org, linus.walleij@...aro.org,
        swboyd@...omium.org, evgreen@...omium.org, mka@...omium.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-gpio@...r.kernel.org, agross@...nel.org, tglx@...utronix.de,
        jason@...edaemon.net, dianders@...omium.org, rnayak@...eaurora.org,
        ilina@...eaurora.org, lsrao@...eaurora.org
Subject: Re: [PATCH 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

Hi,

On 5/23/2020 3:12 PM, Marc Zyngier wrote:
> On 2020-05-22 14:19, Maulik Shah wrote:
>> With 'commit 461c1a7d4733 ("gpiolib: override irq_enable/disable")' 
>> gpiolib
>> overrides irqchip's irq_enable and irq_disable callbacks. If irq_disable
>> callback is implemented then genirq takes unlazy path to disable irq.
>>
>> Underlying irqchip may not want to implement irq_disable callback to 
>> lazy
>> disable irq when client drivers invokes disable_irq(). By overriding
>> irq_disable callback, gpiolib ends up always unlazy disabling IRQ.
>>
>> Allow gpiolib to lazy disable IRQs by overriding irq_disable callback 
>> only
>> if irqchip implemented irq_disable. In cases where irq_disable is not
>> implemented irq_mask is overridden. Similarly override irq_enable 
>> callback
>> only if irqchip implemented irq_enable otherwise irq_unmask is 
>> overridden.
>>
>> Fixes: 461c1a7d47 (gpiolib: override irq_enable/disable)
>> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
>> ---
>>  drivers/gpio/gpiolib.c      | 59 
>> +++++++++++++++++++++++++++++----------------
>>  include/linux/gpio/driver.h | 13 ++++++++++
>>  2 files changed, 51 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> index eaa0e20..a8fdc74 100644
>> --- a/drivers/gpio/gpiolib.c
>> +++ b/drivers/gpio/gpiolib.c
>> @@ -2465,33 +2465,38 @@ static void gpiochip_irq_relres(struct 
>> irq_data *d)
>>      gpiochip_relres_irq(gc, d->hwirq);
>>  }
>>
>> +static void gpiochip_irq_mask(struct irq_data *d)
>> +{
>> +    struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
>> +
>> +    if (chip->irq.irq_mask)
>> +        chip->irq.irq_mask(d);
>> +    gpiochip_disable_irq(chip, d->hwirq);
>> +}
>> +
>> +static void gpiochip_irq_unmask(struct irq_data *d)
>> +{
>> +    struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
>> +
>> +    gpiochip_enable_irq(chip, d->hwirq);
>> +    if (chip->irq.irq_unmask)
>> +        chip->irq.irq_unmask(d);
>> +}
>> +
>>  static void gpiochip_irq_enable(struct irq_data *d)
>>  {
>>      struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>>
>> -    gpiochip_enable_irq(gc, d->hwirq);
>> -    if (gc->irq.irq_enable)
>> -        gc->irq.irq_enable(d);
>> -    else
>> -        gc->irq.chip->irq_unmask(d);
>> +    gpiochip_enable_irq(chip, d->hwirq);
>
> You really never compiled this, did you?
>
> I've stopped looking at this. Please send something that you will have 
> actually tested.
>
>         M.

Apologies.

I did tested out on internal devices based on kernel 5.4 as well as 
linux-next with sc7180.

While posting i somehow taken patch from kernel 5.4 and messed up this 
patch during merge conflicts.

I fixed this in v2 and posted out changes that cleanly applies on latest 
linux-next tag (next-20200521).

Thanks,
Maulik

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