The pca957x driver supports a handful of I2C GPIO expanders from NXP, Maxim, and TI. For the PCA9574 and PCA9575 devices only, the driver resets the GPIO level and direction in the pca957x_probe function. This seems like the wrong thing to do, since it can cause hardware bit twiddles during warm reboots when the chip state and reset values don't match.
This kind of initialization is best left upstream (in a bootloader) or downstream (in userspace). It's also an inconsistency across devices supported by this driver. Signed-off-by: Graeme Smecher <[email protected]> Cc: Grant Likely <[email protected]> Cc: Haojian Zhuang <[email protected]> --- drivers/gpio/gpio-pca953x.c | 11 ----------- 1 file changed, 11 deletions(-) diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index 426c51d..47c08d8 100644 --- a/drivers/gpio/gpio-pca953x.c +++ b/drivers/gpio/gpio-pca953x.c @@ -683,17 +683,6 @@ static int device_pca957x_init(struct pca953x_chip *chip, u32 invert) int ret; u8 val[MAX_BANK]; - /* Let every port in proper state, that could save power */ - memset(val, 0, NBANK(chip)); - pca953x_write_regs(chip, PCA957X_PUPD, val); - memset(val, 0xFF, NBANK(chip)); - pca953x_write_regs(chip, PCA957X_CFG, val); - memset(val, 0, NBANK(chip)); - pca953x_write_regs(chip, PCA957X_OUT, val); - - ret = pca953x_read_regs(chip, PCA957X_IN, val); - if (ret) - goto out; ret = pca953x_read_regs(chip, PCA957X_OUT, chip->reg_output); if (ret) goto out; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
