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Commit 81c2472b authored by Maxim Kiselev's avatar Maxim Kiselev Committed by Greg Kroah-Hartman
Browse files

gpio: pcf857x: Fix missing first interrupt 



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: 6e20a0a4 ("gpio: pcf857x: enable gpio_to_irq() support")
Signed-off-by: default avatarMaxim Kiselev <bigunclemax@gmail.com>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 70dcfb66

drivers/gpio/gpio-pcf857x.c

+1 −1
Original line number Diff line number Diff line
@@ -332,7 +332,7 @@ static int pcf857x_probe(struct i2c_client *client, 
	 * 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 = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);

	if (status < 0)