From: Maxim Kiselev bigunclemax@gmail.com
commit a8002a35935aaefcd6a42ad3289f62bab947f2ca upstream.
If no n_latch value will be provided at driver probe then all pins will be used as an input:
gpio->out = ~n_latch;
In that case initial state for all pins is "one":
gpio->status = gpio->out;
So if pcf857x IRQ happens with change pin value from "zero" to "one" then we miss it, because of "one" from IRQ and "one" from initial state leaves corresponding pin unchanged: change = (gpio->status ^ status) & gpio->irq_enabled;
The right solution will be to read actual state at driver probe.
Cc: stable@vger.kernel.org Fixes: 6e20a0a429bd ("gpio: pcf857x: enable gpio_to_irq() support") Signed-off-by: Maxim Kiselev bigunclemax@gmail.com Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpio/gpio-pcf857x.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/gpio/gpio-pcf857x.c +++ b/drivers/gpio/gpio-pcf857x.c @@ -370,7 +370,7 @@ static int pcf857x_probe(struct i2c_clie * reset state. Otherwise it flags pins to be driven low. */ gpio->out = ~n_latch; - gpio->status = gpio->out; + gpio->status = gpio->read(gpio->client);
status = gpiochip_add(&gpio->chip); if (status < 0)