From: Bartosz Golaszewski bartosz.golaszewski@linaro.org
[ Upstream commit ff0f0d7c6587e38c308be9905e36f86e98fb9c1f ]
regmap_update_bits() can fail so check its return value in wcd_gpio_direction_output() for consistency with the rest of the code and propagate any errors.
Link: https://lore.kernel.org/r/20250709-gpiochip-set-rv-gpio-remaining-v1-2-b8950... Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
Based on my analysis, here's my determination:
**YES**
This commit should be backported to stable kernel trees for the following reasons:
1. **It fixes a real bug**: The `wcd_gpio_direction_output()` function in drivers/gpio/gpio-wcd934x.c was not checking the return value of the first `regmap_update_bits()` call (lines 50-51 in the original code). This could lead to silent failures where the GPIO direction register update fails, but the function continues to update the value register, potentially leaving the GPIO in an inconsistent state.
2. **The fix is minimal and contained**: The change is very small - it only adds 4 lines of code to check the return value and propagate the error. This minimizes the risk of introducing regressions.
3. **Consistency with the rest of the driver**: Looking at the code, other functions in the same driver already properly check regmap operation return values: - `wcd_gpio_get_direction()` checks the return value of `regmap_read()` at line 27-29 - `wcd_gpio_direction_input()` already returns the result of `regmap_update_bits()` directly
4. **Consistency with other GPIO drivers**: My examination of other GPIO drivers (gpio-lp87565.c, gpio-lp873x.c, gpio-tps65912.c, gpio- adp5585.c) shows that properly checking return values from regmap operations in `direction_output` functions is the standard practice.
5. **Potential for real-world impact**: The WCD934x is an audio codec used in Qualcomm SoCs like SDM845. A failure to properly set GPIO direction could cause issues with audio functionality or other peripherals connected through these GPIOs. The bug could manifest as intermittent failures that are hard to debug.
6. **No architectural changes**: The commit doesn't introduce new features or change any APIs. It's purely a bug fix that adds proper error handling.
7. **Clear bug pattern**: The pattern of not checking the first regmap operation but checking (returning) the second one suggests this was an oversight rather than intentional behavior.
The commit follows stable kernel rules by being a clear bug fix that addresses a potential reliability issue without introducing new functionality or making architectural changes.
drivers/gpio/gpio-wcd934x.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpio-wcd934x.c b/drivers/gpio/gpio-wcd934x.c index 97e6caedf1f3..c00968ce7a56 100644 --- a/drivers/gpio/gpio-wcd934x.c +++ b/drivers/gpio/gpio-wcd934x.c @@ -45,9 +45,12 @@ static int wcd_gpio_direction_output(struct gpio_chip *chip, unsigned int pin, int val) { struct wcd_gpio_data *data = gpiochip_get_data(chip); + int ret;
- regmap_update_bits(data->map, WCD_REG_DIR_CTL_OFFSET, - WCD_PIN_MASK(pin), WCD_PIN_MASK(pin)); + ret = regmap_update_bits(data->map, WCD_REG_DIR_CTL_OFFSET, + WCD_PIN_MASK(pin), WCD_PIN_MASK(pin)); + if (ret) + return ret;
return regmap_update_bits(data->map, WCD_REG_VAL_CTL_OFFSET, WCD_PIN_MASK(pin),