2020-05-14 13:03:03

by Rodrigo Alencar

Subject: [PATCH] gpio: gpio-max730x: bring gpiochip_add_data after port config

gpiochip_add_data being called before might cause premature calls of
the gpiochip operations before the port_config values are initialized,
which would possibily write zeros to port gonfiguration registers,
an operation not allowed. For example, if there are gpio-hog nodes
in a device-tree, the sequence of function calls are performed

gpiochip_add_data
of_gpiochip_add
of_gpiochip_scan_gpios
of_gpiochip_add_hog
gpiod_hog
gpiochip_request_own_desc
gpiod_configure_flags
gpiod_direction_output/gpiod_direction_input

which would call later the gpiochip operation direction_output or
direction_input prior the port_config[] initialization.

Moreover, gpiochip_get_data is replaced by the container_of macro
inside the gpiochip operations, which would allow the calling of
max7301_direction_input prior to gpiochip_add_data

Signed-off-by: Rodrigo Alencar <[email protected]>
---
drivers/gpio/gpio-max730x.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpio-max730x.c b/drivers/gpio/gpio-max730x.c
index 1e1935c51096..b8c1fe20f49a 100644
--- a/drivers/gpio/gpio-max730x.c
+++ b/drivers/gpio/gpio-max730x.c
@@ -47,7 +47,7 @@

static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
{
- struct max7301 *ts = gpiochip_get_data(chip);
+ struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits, pin_config;
int ret;
@@ -89,7 +89,7 @@ static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
int value)
{
- struct max7301 *ts = gpiochip_get_data(chip);
+ struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits;
int ret;
@@ -189,10 +189,6 @@ int __max730x_probe(struct max7301 *ts)
ts->chip.parent = dev;
ts->chip.owner = THIS_MODULE;

- ret = gpiochip_add_data(&ts->chip, ts);
- if (ret)
- goto exit_destroy;
-
/*
* initialize pullups according to platform data and cache the
* register values for later use.
@@ -214,7 +210,9 @@ int __max730x_probe(struct max7301 *ts)
}
}

- return ret;
+ ret = gpiochip_add_data(&ts->chip, ts);
+ if (!ret)
+ return ret;

exit_destroy:
mutex_destroy(&ts->lock);
--
2.23.0.rc1

2020-05-22 15:04:39

by Bartosz Golaszewski

Subject: Re: [PATCH] gpio: gpio-max730x: bring gpiochip_add_data after port config

czw., 14 maj 2020 o 15:00 Rodrigo Alencar
<[email protected]> napisał(a):
>
> gpiochip_add_data being called before might cause premature calls of
> the gpiochip operations before the port_config values are initialized,
> which would possibily write zeros to port gonfiguration registers,
> an operation not allowed. For example, if there are gpio-hog nodes
> in a device-tree, the sequence of function calls are performed
>
> gpiochip_add_data
> of_gpiochip_add
> of_gpiochip_scan_gpios
> of_gpiochip_add_hog
> gpiod_hog
> gpiochip_request_own_desc
> gpiod_configure_flags
> gpiod_direction_output/gpiod_direction_input
>
> which would call later the gpiochip operation direction_output or
> direction_input prior the port_config[] initialization.
>
> Moreover, gpiochip_get_data is replaced by the container_of macro
> inside the gpiochip operations, which would allow the calling of
> max7301_direction_input prior to gpiochip_add_data
>
> Signed-off-by: Rodrigo Alencar <[email protected]>

Applied with some tweaks to the commit message.

Bartosz