Re: [PATCH wireless-next 1/2] wifi: wfx: fix possible device hang during init

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missed firmware startup interrupt on SPI platforms due to late IRQ subscription.
--

commit b2aaae6022fa921df221babdf79ea3e5f12e766f
Author: Jérôme Pouiller <jerome.pouiller@silabs.com>

wifi: wfx: fix possible device hang during init

This patch modifies the device initialization sequence to limit data
polling to out-of-band IRQ setups. It attempts to prevent a hardware lockup
that occurs if an IRQ fires while the host is reading the control register.

> diff --git a/drivers/net/wireless/silabs/wfx/main.c b/drivers/net/wireless/silabs/wfx/main.c
> index dda36e41eed13..da30e8f481ada 100644
> --- a/drivers/net/wireless/silabs/wfx/main.c
> +++ b/drivers/net/wireless/silabs/wfx/main.c

[ ... ]

> @@ -374,12 +373,19 @@ int wfx_probe(struct wfx_dev *wdev)
>  	if (err)
>  		goto bh_unregister;
>  
> -	wfx_bh_poll_irq(wdev);
> +	if (wdev->poll_irq) {
> +		wfx_bh_poll_irq(wdev);
> +	} else {
> +		err = wdev->hwbus_ops->irq_subscribe(wdev->hwbus_priv);
> +		if (err)
> +			goto bh_unregister;
> +	}
> +
>  	err = wait_for_completion_timeout(&wdev->firmware_ready, 1 * HZ);

[Severity: High]
The commit message states that the IRQ is subscribed before the first
exchange with the device. However, looking at wfx_probe(), the code just
above this snippet calls wfx_init_device(), which conducts the first
exchanges and unmasks device-side interrupts.

Since irq_subscribe() is only called after wfx_init_device() finishes, is
there a race window here?

If the device asserts the firmware-ready interrupt during this gap before
the host OS registers the IRQ handler, could the edge be permanently lost
(e.g., on SPI platforms using edge-triggered interrupts)? This seems like it
could cause the subsequent wait_for_completion_timeout() to timeout and 
hang the initialization.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260831164056.47683-1-jerome.pouiller@silabs.com?part=1