From f07798d7bb9c46d17d80103fb772fd2c75d47919 Mon Sep 17 00:00:00 2001 From: Shiji Yang Date: Tue, 25 Jun 2024 09:19:49 +0800 Subject: [PATCH] gpio: mmio: do not calculate bgpio_bits via "ngpios" bgpio_bits must be aligned with the data bus width. For example, on a 32 bit big endian system and we only have 16 GPIOs. If we only assume bgpio_bits=16 we can never control the GPIO because the base address is the lowest address. low address high address ------------------------------------------------- | byte3 | byte2 | byte1 | byte0 | ------------------------------------------------- | NaN | NaN | gpio8-15 | gpio0-7 | ------------------------------------------------- Fixes: 55b2395e4e92 ("gpio: mmio: handle "ngpios" properly in bgpio_init()") Fixes: https://github.com/openwrt/openwrt/issues/15739 Reported-by: Mark Mentovai Signed-off-by: Shiji Yang Suggested-By: Mark Mentovai Reviewed-by: Jonas Gorski Tested-by: Lóránd Horváth Reviewed-by: Linus Walleij Link: https://lore.kernel.org/r/TYCP286MB089577B47D70F0AB25ABA6F5BCD52@TYCP286MB0895.JPNP286.PROD.OUTLOOK.COM Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpio-mmio.c | 2 -- 1 file changed, 2 deletions(-) --- a/drivers/gpio/gpio-mmio.c +++ b/drivers/gpio/gpio-mmio.c @@ -622,8 +622,6 @@ int bgpio_init(struct gpio_chip *gc, str ret = gpiochip_get_ngpios(gc, dev); if (ret) gc->ngpio = gc->bgpio_bits; - else - gc->bgpio_bits = roundup_pow_of_two(round_up(gc->ngpio, 8)); ret = bgpio_setup_io(gc, dat, set, clr, flags); if (ret)