From 6e6d30ab723843fea8d9df368b35e89327f33c11 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Tue, 19 Oct 2021 11:23:43 +0100 Subject: [PATCH] gpio: bcm-virt: Fix the get() method The get() method does not understand the on-the-wire encoding of the remote GPIO states, thinking they are simple on/off bits when they are really pairs of 16-bit counts. Rewrite the get() handler to return the value last written, which will eventually match the actual GPIO state if there are no other changes. See: https://github.com/raspberrypi/linux/issues/4638 Signed-off-by: Phil Elwell --- drivers/gpio/gpio-bcm-virt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/gpio/gpio-bcm-virt.c +++ b/drivers/gpio/gpio-bcm-virt.c @@ -49,7 +49,7 @@ static int brcmvirt_gpio_get(struct gpio unsigned v; gpio = container_of(gc, struct brcmvirt_gpio, gc); v = readl(gpio->ts_base + off); - return (v >> off) & 1; + return (s16)((v >> 16) - v) > 0; } static void brcmvirt_gpio_set(struct gpio_chip *gc, unsigned off, int val)