[PATCH] gpio: pcf857x: Fix missing first interrupt

[Maksim Kiselev <bigunclemax@xxxxxxxxx>]

From: Maxim Kiselev <bigunclemax@xxxxxxxxx>
Date: Tue, 16 Feb 2021 17:00:58 +0300
Subject: [PATCH] gpio: pcf857x: Fix missing first interrupt

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.

Fixies: commit 6e20a0a429bd ("gpio: pcf857x: enable gpio_to_irq() support")
Signed-off-by: Maxim Kiselev <bigunclemax@xxxxxxxxx>
---
drivers/gpio/gpio-pcf857x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
index a2a8d155c75e3..b7568ee33696d 100644
--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -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) {
--
2.27.0