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generic: gpio: fix broken GPIO for big endian CPUs 

Align the "bgpio_bits" with the data bus width.

Fixes: https://github.com/openwrt/openwrt/issues/15739
Signed-off-by: Shiji Yang <yangshiji66@qq.com>
Suggested-By: Mark Mentovai <mark@mentovai.com>
Tested-by: Lóránd Horváth <lorand.horvath82@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/15784
Signed-off-by: Robert Marko <robimarko@gmail.com>
This commit is contained in:
Shiji Yang 2024-07-04 18:35:50 +08:00 committed by Robert Marko
parent ee01666cd3
commit d836a688d1
1 changed files with 42 additions and 0 deletions
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42
target/linux/generic/backport-6.6/801-v6.11-gpio-mmio-do-not-calculate-bgpio_bits-via-ngpios.patch Normal file
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@ -0,0 +1,42 @@
From f07798d7bb9c46d17d80103fb772fd2c75d47919 Mon Sep 17 00:00:00 2001
From: Shiji Yang <yangshiji66@outlook.com>
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 <mark@mentovai.com>
Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Suggested-By: Mark Mentovai <mark@mentovai.com>
Reviewed-by: Jonas Gorski <jonas.gorski@gmail.com>
Tested-by: Lóránd Horváth <lorand.horvath82@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/TYCP286MB089577B47D70F0AB25ABA6F5BCD52@TYCP286MB0895.JPNP286.PROD.OUTLOOK.COM
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
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)