Re: [PATCH v7 2/2] rtc: Add Raspberry Pi 5 RTC driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] dt: brittle string comparison on model property instead of compatible match
--

commit 785b9ba4b6f1ff162b94712e510b9c39d0c39474
Author: Sander Speetjens <sander.speetjens@gmail.com>

rtc: Add Raspberry Pi 5 RTC driver

Upstreaming the downstream Raspberry Pi 5 RTC driver. This driver supports
the custom DA9091, which is accessed through the firmware mailbox.

> diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
> index 0aa322e9a2e73..a35f00c6fb2c1 100644
> --- a/drivers/firmware/raspberrypi.c
> +++ b/drivers/firmware/raspberrypi.c
[ ... ]
> @@ -231,6 +232,27 @@ static void rpi_register_clk_driver(struct device *dev)
>  						-1, NULL, 0);
>  }
>  
> +static void rpi_register_rtc_driver(struct device *dev)
> +{
> +	struct device_node *firmware;
> +
> +	// Check if our model is a Raspberry Pi 5, as the RTC is only present on that model.
> +	const char *model = of_get_property(of_root, "model", NULL);
> +
> +	if (!model || strncmp(model, "Raspberry Pi 5", 14) != 0)

[Severity: Medium]
Is it safe to use strncmp() on the human-readable "model" property to
identify the board here in rpi_register_rtc_driver()?

Since the check only compares the first 14 characters, could this incorrectly
match unrecognized future devices like 'Raspberry Pi 500' and improperly
register the RTC?

Would it be better to use of_machine_is_compatible() with a compatible string
match instead, which is more robust against formatting changes?

> +		return;
> +
> +	firmware = of_get_compatible_child(dev->of_node,
> +					   "raspberrypi,firmware-rtc");

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260930083922.484885-1-sander.speetjens@gmail.com?part=2