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gpio: vf610: add locking to gpio direction functions

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Add locking to `vf610_gpio_direction_input|output()` functions. Without
this locking, a race condition exists between concurrent calls to these
functions, potentially leading to incorrect GPIO direction settings.

To verify the correctness of this fix, a `trylock` patch was applied,
where after a couple of reboots the race was confirmed. I.e., one user
had to wait before acquiring the lock. With this patch the race has not
been encountered. It's worth mentioning that any type of debugging
(printing, tracing, etc.) would "resolve"/hide the issue.

Fixes: 659d8a6231 ("gpio: vf610: add imx7ulp support")
Signed-off-by: Johan Korsnes <johan.korsnes@remarkable.no>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250217091643.679644-1-johan.korsnes@remarkable.no
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Johan Korsnes 2025-02-17 10:16:43 +01:00 • committed by Bartosz Golaszewski
parent 9d846b1aeb
commit 4e667a1968
1 changed files with 4 additions and 0 deletions
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4
drivers/gpio/gpio-vf610.c
View file

@ -36,6 +36,7 @@ struct vf610_gpio_port {
struct clk *clk_port;
struct clk *clk_gpio;
int irq;
spinlock_t lock; /* protect gpio direction registers */
};
#define GPIO_PDOR 0x00
@ -124,6 +125,7 @@ static int vf610_gpio_direction_input(struct gpio_chip *chip, unsigned int gpio)
u32 val;
if (port->sdata->have_paddr) {
guard(spinlock_irqsave)(&port->lock);
val = vf610_gpio_readl(port->gpio_base + GPIO_PDDR);
val &= ~mask;
vf610_gpio_writel(val, port->gpio_base + GPIO_PDDR);
@ -142,6 +144,7 @@ static int vf610_gpio_direction_output(struct gpio_chip *chip, unsigned int gpio
vf610_gpio_set(chip, gpio, value);
if (port->sdata->have_paddr) {
guard(spinlock_irqsave)(&port->lock);
val = vf610_gpio_readl(port->gpio_base + GPIO_PDDR);
val |= mask;
vf610_gpio_writel(val, port->gpio_base + GPIO_PDDR);
@ -297,6 +300,7 @@ static int vf610_gpio_probe(struct platform_device *pdev)
return -ENOMEM;
port->sdata = device_get_match_data(dev);
spin_lock_init(&port->lock);
dual_base = port->sdata->have_dual_base;