linux-kernel - Re: [v2] gpio: dwapb: mask/unmask IRQ when disable/enale it

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Message-ID: <26nje24sbwccuenarcttuskk7q2ngyxun2nbuynd32ylcozc5y@aasey6najeji>
Date: Mon, 18 Dec 2023 13:10:08 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: xiongxin <xiongxin@...inos.cn>
Cc: hoan@...amperecomputing.com, linus.walleij@...aro.org, brgl@...ev.pl, 
	andy@...nel.org, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Riwen Lu <luriwen@...inos.cn>
Subject: Re: [v2] gpio: dwapb: mask/unmask IRQ when disable/enale it

On Mon, Dec 18, 2023 at 04:12:46PM +0800, xiongxin wrote:
> In the hardware implementation of the i2c hid driver based on dwapb gpio
> irq, when the user continues to use the i2c hid device in the suspend
> process, the i2c hid interrupt will be masked after the resume process
> is finished.
> 
> This is because the disable_irq()/enable_irq() of the dwapb gpio driver
> does not synchronize the irq mask register state. In normal use of the
> i2c hid procedure, the gpio irq irq_mask()/irq_unmask() functions are
> called in pairs. In case of an exception, i2c_hid_core_suspend() calls
> disable_irq() to disable the gpio irq. With low probability, this causes
> irq_unmask() to not be called, which causes the gpio irq to be masked
> and not unmasked in enable_irq(), raising an exception.
> 
> Add synchronization to the masked register state in the
> dwapb_irq_enable()/dwapb_irq_disable() function. mask the gpio irq
> before disabling it. After enabling the gpio irq, unmask the irq.
> 
> Fixes: 7779b3455697 ("gpio: add a driver for the Synopsys DesignWare APB GPIO block")
> Signed-off-by: xiongxin <xiongxin@...inos.cn>
> Signed-off-by: Riwen Lu <luriwen@...inos.cn>
> Tested-by: xiongxin <xiongxin@...inos.cn>
> ---
>  drivers/gpio/gpio-dwapb.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index 4a4f61bf6c58..8c59332429c2 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -282,13 +282,15 @@ static void dwapb_irq_enable(struct irq_data *d)
>  {
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>  	struct dwapb_gpio *gpio = to_dwapb_gpio(gc);

> +	irq_hw_number_t hwirq = irqd_to_hwirq(d);

Thanks for submitting the patch. I wasn't sure which way was better:
define a "mask" or "hwirq" local vars with respective semantics. From
my point of view both were correct with the first version being more
optimized and the second one making enable()/disable() methods looking
alike the mask()/unmask() functions. No objections against you
implementing the second version. So

Acked-by: Serge Semin <fancer.lancer@...il.com>

-Serge(y)

>  	unsigned long flags;
>  	u32 val;
>  
>  	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
> -	val = dwapb_read(gpio, GPIO_INTEN);
> -	val |= BIT(irqd_to_hwirq(d));
> +	val = dwapb_read(gpio, GPIO_INTEN) | BIT(hwirq);
>  	dwapb_write(gpio, GPIO_INTEN, val);
> +	val = dwapb_read(gpio, GPIO_INTMASK) & ~BIT(hwirq);
> +	dwapb_write(gpio, GPIO_INTMASK, val);
>  	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
> @@ -296,12 +298,14 @@ static void dwapb_irq_disable(struct irq_data *d)
>  {
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>  	struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> +	irq_hw_number_t hwirq = irqd_to_hwirq(d);
>  	unsigned long flags;
>  	u32 val;
>  
>  	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
> -	val = dwapb_read(gpio, GPIO_INTEN);
> -	val &= ~BIT(irqd_to_hwirq(d));
> +	val = dwapb_read(gpio, GPIO_INTMASK) | BIT(hwirq);
> +	dwapb_write(gpio, GPIO_INTMASK, val);
> +	val = dwapb_read(gpio, GPIO_INTEN) & ~BIT(hwirq);
>  	dwapb_write(gpio, GPIO_INTEN, val);
>  	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
> -- 
> 2.34.1
>