linux-kernel - Re: [PATCH] pinctrl: qcom: msm: mark certain pins as invalid for interrupts

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Message-ID: <3i6ni6jfq7vzij5cj4h35sy4ceegeekuv3lr5b3nmyqtheky6q@mlrspoyavfwt>
Date: Wed, 11 Jun 2025 10:03:23 -0500
From: Bjorn Andersson <andersson@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>, 
	linux-arm-msm@...r.kernel.org, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, stable@...r.kernel.org
Subject: Re: [PATCH] pinctrl: qcom: msm: mark certain pins as invalid for
 interrupts

On Wed, Jun 11, 2025 at 04:39:11PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> When requesting pins whose intr_detection_width setting is not 1 or 2
> for interrupts (for example by running `gpiomon -c 0 113` on RB2), we'll
> hit a BUG() in msm_gpio_irq_set_type(). Potentially crashing the kernel
> due to an invalid request from user-space is not optimal, so let's go
> through the pins and mark those that would fail the check as invalid for
> the irq chip as we should not even register them as available irqs.
> 

I had to go dig into the code to understand why there is a problem with
GPIO 113 on RB2 (i.e. UFS_RESET on SM6115)... I think it would have been
better to document the actual reason for the problem, which is:

"The UFS_RESET pin doesn't have interrupt logic, but is registered as a
GPIO. Requesting the interrupt of this pin hits a BUG() in
msm_gpio_irq_set_type() because intr_detection_width is invalid"

> This function can be extended if we determine that there are more
> corner-cases like this.
> 

Reviewed-by: Bjorn Andersson <andersson@...nel.org>

Regards,
Bjorn

> Fixes: f365be092572 ("pinctrl: Add Qualcomm TLMM driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/pinctrl/qcom/pinctrl-msm.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
> index f012ea88aa22c..77e0c2f023455 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -1038,6 +1038,24 @@ static bool msm_gpio_needs_dual_edge_parent_workaround(struct irq_data *d,
>  	       test_bit(d->hwirq, pctrl->skip_wake_irqs);
>  }
>  
> +static void msm_gpio_irq_init_valid_mask(struct gpio_chip *gc,
> +					 unsigned long *valid_mask,
> +					 unsigned int ngpios)
> +{
> +	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> +	const struct msm_pingroup *g;
> +	int i;
> +
> +	bitmap_fill(valid_mask, ngpios);
> +
> +	for (i = 0; i < ngpios; i++) {
> +		g = &pctrl->soc->groups[i];
> +		if (g->intr_detection_width != 1 &&
> +		    g->intr_detection_width != 2)
> +			clear_bit(i, valid_mask);
> +	}
> +}
> +
>  static int msm_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>  {
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> @@ -1441,6 +1459,7 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>  	girq->default_type = IRQ_TYPE_NONE;
>  	girq->handler = handle_bad_irq;
>  	girq->parents[0] = pctrl->irq;
> +	girq->init_valid_mask = msm_gpio_irq_init_valid_mask;
>  
>  	ret = gpiochip_add_data(&pctrl->chip, pctrl);
>  	if (ret) {
> -- 
> 2.48.1
>