Commit 2aa8ccab authored by Hugo Villeneuve's avatar Hugo Villeneuve Committed by Bartosz Golaszewski
Browse files

gpio: pca953x: use regmap_update_bits() to improve performance 



Using regmap_update_bits() allows to reduce the number of I2C transfers
when updating bits that haven't changed on non-volatile registers.

For example on a PCAL6416, when changing a GPIO direction from input to
output, the number of I2C transfers can be reduced from 4 to just 1 if
the pull resistors configuration hasn't changed and the output value
is the same as before.

Signed-off-by: default avatarHugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20250714133730.6353-1-hugo@hugovil.com


Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent e70513bd

drivers/gpio/gpio-pca953x.c

+10 −10
Original line number Diff line number Diff line
@@ -611,9 +611,9 @@ static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off) 
	guard(mutex)(&chip->i2c_lock);



	if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)

		return regmap_write_bits(chip->regmap, dirreg, bit, 0);

		return regmap_update_bits(chip->regmap, dirreg, bit, 0);



	return regmap_write_bits(chip->regmap, dirreg, bit, bit);

	return regmap_update_bits(chip->regmap, dirreg, bit, bit);

}



static int pca953x_gpio_direction_output(struct gpio_chip *gc,
@@ -628,7 +628,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc, 
	guard(mutex)(&chip->i2c_lock);



	/* set output level */

	ret = regmap_write_bits(chip->regmap, outreg, bit, val ? bit : 0);

	ret = regmap_update_bits(chip->regmap, outreg, bit, val ? bit : 0);

	if (ret)

		return ret;
@@ -637,9 +637,9 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc, 
	 * (in/out logic is inverted on TCA6418)

	 */

	if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)

		return regmap_write_bits(chip->regmap, dirreg, bit, bit);

		return regmap_update_bits(chip->regmap, dirreg, bit, bit);



	return regmap_write_bits(chip->regmap, dirreg, bit, 0);

	return regmap_update_bits(chip->regmap, dirreg, bit, 0);

}



static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
@@ -667,7 +667,7 @@ static int pca953x_gpio_set_value(struct gpio_chip *gc, unsigned int off, 


	guard(mutex)(&chip->i2c_lock);



	return regmap_write_bits(chip->regmap, outreg, bit, val ? bit : 0);

	return regmap_update_bits(chip->regmap, outreg, bit, val ? bit : 0);

}



static int pca953x_gpio_get_direction(struct gpio_chip *gc, unsigned off)
@@ -751,9 +751,9 @@ static int pca953x_gpio_set_pull_up_down(struct pca953x_chip *chip, 


	/* Configure pull-up/pull-down */

	if (param == PIN_CONFIG_BIAS_PULL_UP)

		ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, bit);

		ret = regmap_update_bits(chip->regmap, pull_sel_reg, bit, bit);

	else if (param == PIN_CONFIG_BIAS_PULL_DOWN)

		ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, 0);

		ret = regmap_update_bits(chip->regmap, pull_sel_reg, bit, 0);

	else

		ret = 0;

	if (ret)
@@ -761,9 +761,9 @@ static int pca953x_gpio_set_pull_up_down(struct pca953x_chip *chip, 


	/* Disable/Enable pull-up/pull-down */

	if (param == PIN_CONFIG_BIAS_DISABLE)

		return regmap_write_bits(chip->regmap, pull_en_reg, bit, 0);

		return regmap_update_bits(chip->regmap, pull_en_reg, bit, 0);

	else

		return regmap_write_bits(chip->regmap, pull_en_reg, bit, bit);

		return regmap_update_bits(chip->regmap, pull_en_reg, bit, bit);

}



static int pca953x_gpio_set_config(struct gpio_chip *gc, unsigned int offset,