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gpio: pcf857x: Fix missing first interrupt

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commit a8002a3593 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: 6e20a0a429 ("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>
This commit is contained in:
Maxim Kiselev 2021-02-17 14:10:00 +01:00 committed by Greg Kroah-Hartman
parent 548d83e8b6
commit 67e7c64b47
1 changed files with 1 additions and 1 deletions
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2
drivers/gpio/gpio-pcf857x.c
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@ -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);
/* Enable irqchip if we have an interrupt */
if (client->irq) {