Re: [PATCH v3 03/10] ARM: s3c: register and attach software nodes for Samsung gpio_chips

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The 4-bit and 4-bit2 GPIO direction configuration functions perform read-modify-write operations on shared configuration registers without holding the chip's spinlock, leading to race conditions.
--

--- Patch [3]: [PATCH v3 03/10] ARM: s3c: register and attach software nodes for Samsung gpio_chips ---
commit 8053fb79cb15e3c5c2e66691008b5adc30b3e152
Author: Dmitry Torokhov <dmitry.torokhov@gmail.com>

ARM: s3c: register and attach software nodes for Samsung gpio_chips

This commit defines and registers software nodes for the Samsung GPIO chips on
legacy platforms. It attaches the matching software node to each gpio_chip's
fwnode during registration, providing the infrastructure to convert board files
and drivers to use software nodes instead of legacy platform data.

> diff --git a/arch/arm/mach-s3c/gpio-samsung.c b/arch/arm/mach-s3c/gpio-samsung.c
> --- a/arch/arm/mach-s3c/gpio-samsung.c
> +++ b/arch/arm/mach-s3c/gpio-samsung.c

[ ... ]

> @@ -659,49 +695,49 @@ static struct samsung_gpio_chip s3c64xx_gpios_4bit[] = {
>  		.chip	= {
>  			.base	= S3C64XX_GPA(0),
>  			.ngpio	= S3C64XX_GPIO_A_NR,
> -			.label	= "GPA",
>  		},
> +		.swnode	= SAMSUNG_GPIO_NODE('A'),

[Severity: High]
This is a pre-existing issue, but since we are updating the 4-bit GPIO chip
registrations here, should the underlying 4-bit configuration functions be
updated to use the chip->lock?

Currently, functions like samsung_gpiolib_4bit_input() perform
read-modify-write operations on shared configuration registers without locking:

samsung_gpiolib_4bit_input() {
    ...
    con = __raw_readl(base + GPIOCON_OFF);
    if (ourchip->bitmap_gpio_int & BIT(offset))
        con |= 0xf << con_4bit_shift(offset);
    else
        con &= ~(0xf << con_4bit_shift(offset));
    __raw_writel(con, base + GPIOCON_OFF);
    ...
}

Similar unprotected read-modify-write sequences exist in
samsung_gpiolib_4bit_output() (for both GPIOCON and GPIODAT) and
samsung_gpiolib_4bit2_input().

If two threads concurrently attempt to change the direction of different
GPIO pins in the same bank, could this lead to lost or corrupted
configuration updates?

>  	}, {

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260711-samsung-kp-v3-0-b2fcaba77aff@gmail.com?part=3