The patch titled drivers/gpio/pca953x.c: add a mutex to fix race condition has been added to the -mm tree. Its filename is drivers-gpio-pca953xc-add-a-mutex-to-fix-race-condition.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: drivers/gpio/pca953x.c: add a mutex to fix race condition Add a mutex to register communication and handling. Without the mutex, GPIOs didn't switch as expected when toggled in a fast sequence of status changes of multiple outputs. Signed-off-by: Roland Stigge <stigge@xxxxxxxxx> Cc: Grant Likely <grant.likely@xxxxxxxxxxxx> Cc: Marc Zyngier <maz@xxxxxxxxxxxxxxx> Cc: Ben Gardner <bgardner@xxxxxxxxxx> Cc: eric miao <eric.y.miao@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/gpio/pca953x.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff -puN drivers/gpio/pca953x.c~drivers-gpio-pca953xc-add-a-mutex-to-fix-race-condition drivers/gpio/pca953x.c --- a/drivers/gpio/pca953x.c~drivers-gpio-pca953xc-add-a-mutex-to-fix-race-condition +++ a/drivers/gpio/pca953x.c @@ -60,6 +60,7 @@ struct pca953x_chip { unsigned gpio_start; uint16_t reg_output; uint16_t reg_direction; + struct mutex i2c_lock; #ifdef CONFIG_GPIO_PCA953X_IRQ struct mutex irq_lock; @@ -119,13 +120,17 @@ static int pca953x_gpio_direction_input( chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); reg_val = chip->reg_direction | (1u << off); ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val); if (ret) - return ret; + goto exit; chip->reg_direction = reg_val; - return 0; + ret = 0; +exit: + mutex_unlock(&chip->i2c_lock); + return ret; } static int pca953x_gpio_direction_output(struct gpio_chip *gc, @@ -137,6 +142,7 @@ static int pca953x_gpio_direction_output chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); /* set output level */ if (val) reg_val = chip->reg_output | (1u << off); @@ -145,7 +151,7 @@ static int pca953x_gpio_direction_output ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val); if (ret) - return ret; + goto exit; chip->reg_output = reg_val; @@ -153,10 +159,13 @@ static int pca953x_gpio_direction_output reg_val = chip->reg_direction & ~(1u << off); ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val); if (ret) - return ret; + goto exit; chip->reg_direction = reg_val; - return 0; + ret = 0; +exit: + mutex_unlock(&chip->i2c_lock); + return ret; } static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off) @@ -167,7 +176,9 @@ static int pca953x_gpio_get_value(struct chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); ret = pca953x_read_reg(chip, PCA953X_INPUT, ®_val); + mutex_unlock(&chip->i2c_lock); if (ret < 0) { /* NOTE: diagnostic already emitted; that's all we should * do unless gpio_*_value_cansleep() calls become different @@ -187,6 +198,7 @@ static void pca953x_gpio_set_value(struc chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); if (val) reg_val = chip->reg_output | (1u << off); else @@ -194,9 +206,11 @@ static void pca953x_gpio_set_value(struc ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val); if (ret) - return; + goto exit; chip->reg_output = reg_val; +exit: + mutex_unlock(&chip->i2c_lock); } static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios) @@ -517,6 +531,8 @@ static int __devinit pca953x_probe(struc chip->names = pdata->names; + mutex_init(&chip->i2c_lock); + /* initialize cached registers from their original values. * we can't share this chip with another i2c master. */ _ Patches currently in -mm which might be from stigge@xxxxxxxxx are linux-next.patch drivers-gpio-pca953xc-add-a-mutex-to-fix-race-condition.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html