This is a note to let you know that I've just added the patch titled
gpio: pcf857x: Fix missing first interrupt
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpio-pcf857x-fix-missing-first-interrupt.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a8002a35935aaefcd6a42ad3289f62bab947f2ca Mon Sep 17 00:00:00 2001
From: Maxim Kiselev <bigunclemax@xxxxxxxxx>
Date: Wed, 17 Feb 2021 14:10:00 +0100
Subject: gpio: pcf857x: Fix missing first interrupt
From: Maxim Kiselev <bigunclemax@xxxxxxxxx>
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@xxxxxxxxxxxxxxx
Fixes: 6e20a0a429bd ("gpio: pcf857x: enable gpio_to_irq() support")
Signed-off-by: Maxim Kiselev <bigunclemax@xxxxxxxxx>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)
Patches currently in stable-queue which might be from bigunclemax@xxxxxxxxx are
queue-4.4/gpio-pcf857x-fix-missing-first-interrupt.patch
