Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
Fixes: 36fb7218e878 ("gpio: exar: switch to using regmap") Signed-off-by: Sai Kumar Cholleti skmr537@gmail.com Signed-off-by: Matthew McClain mmcclain@noprivs.com Cc: stable@vger.kernel.org --- drivers/gpio/gpio-exar.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c index 5170fe7599cd..dfc7a9ca3e62 100644 --- a/drivers/gpio/gpio-exar.c +++ b/drivers/gpio/gpio-exar.c @@ -99,11 +99,13 @@ static void exar_set_value(struct gpio_chip *chip, unsigned int offset, struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip); unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset); unsigned int bit = exar_offset_to_bit(exar_gpio, offset); + unsigned int bit_value = value ? BIT(bit) : 0;
- if (value) - regmap_set_bits(exar_gpio->regmap, addr, BIT(bit)); - else - regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit)); + /* + * regmap_write_bits forces value to be written when an external + * pull up/down might otherwise indicate value was already set + */ + regmap_write_bits(exar_gpio->regmap, addr, BIT(bit), bit_value); }
static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
On Mon, Nov 04, 2024 at 09:17:57PM +0530, Sai Kumar Cholleti wrote:
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction
This...
$ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction
...this...
$ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction
...this...
$ cat /sys/class/gpio/gpio351/value 1
Fixes: 36fb7218e878 ("gpio: exar: switch to using regmap")
...and this lines have a trailing space.
Signed-off-by: Sai Kumar Cholleti skmr537@gmail.com Signed-off-by: Matthew McClain mmcclain@noprivs.com
Hmm... Missing Co-developed-by? This SoB chain puzzles me a bit, the committer should go last AFAIR.
...
- /*
* regmap_write_bits forces value to be written when an external
regmap_write_bits()
* pull up/down might otherwise indicate value was already set
Missing period at the end.
*/
...
Other than above LGTM.
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
Fixes: 36fb7218e878 ("gpio: exar: switch to using regmap") Co-developed-by: Matthew McClain mmcclain@noprivs.com Signed-off-by: Matthew McClain mmcclain@noprivs.com Signed-off-by: Sai Kumar Cholleti skmr537@gmail.com Cc: stable@vger.kernel.org --- drivers/gpio/gpio-exar.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c index 5170fe7599cd..d5909a4f0433 100644 --- a/drivers/gpio/gpio-exar.c +++ b/drivers/gpio/gpio-exar.c @@ -99,11 +99,13 @@ static void exar_set_value(struct gpio_chip *chip, unsigned int offset, struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip); unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset); unsigned int bit = exar_offset_to_bit(exar_gpio, offset); + unsigned int bit_value = value ? BIT(bit) : 0;
- if (value) - regmap_set_bits(exar_gpio->regmap, addr, BIT(bit)); - else - regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit)); + /* + * regmap_write_bits() forces value to be written when an external + * pull up/down might otherwise indicate value was already set. + */ + regmap_write_bits(exar_gpio->regmap, addr, BIT(bit), bit_value); }
static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
On Tue, Nov 05, 2024 at 12:45:23PM +0530, Sai Kumar Cholleti wrote:
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
On Tue, Nov 05, 2024 at 04:39:38PM +0200, Andy Shevchenko wrote:
On Tue, Nov 05, 2024 at 12:45:23PM +0530, Sai Kumar Cholleti wrote:
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Does this need to be applied, Bart? Seems it is missed in your branches...
On Tue, Nov 12, 2024 at 5:09 PM Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Tue, Nov 05, 2024 at 04:39:38PM +0200, Andy Shevchenko wrote:
On Tue, Nov 05, 2024 at 12:45:23PM +0530, Sai Kumar Cholleti wrote:
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default).
regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high.
The same can happen when a GPIO is pulled low, but the scenario is a little more complicated.
$ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
$ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0
$ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1
Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Does this need to be applied, Bart? Seems it is missed in your branches...
Maybe if the author used get_maintainers.pl as they should, I would have noticed this earlier?
I have some other fixes to pick up so I'll send this later in the merge window.
Bart
On Mon, Nov 18, 2024 at 12:00:00PM +0100, Bartosz Golaszewski wrote:
On Tue, Nov 12, 2024 at 5:09 PM Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Tue, Nov 05, 2024 at 04:39:38PM +0200, Andy Shevchenko wrote:
On Tue, Nov 05, 2024 at 12:45:23PM +0530, Sai Kumar Cholleti wrote:
...
Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Does this need to be applied, Bart? Seems it is missed in your branches...
Maybe if the author used get_maintainers.pl as they should, I would have noticed this earlier?
Ah good catch!
Sai, FYI, I use my script [1] which does all required stuff for me. Feel free to use it, patch, comment, etc...
I have some other fixes to pick up so I'll send this later in the merge window.
Thanks!
[1]: https://github.com/andy-shev/home-bin-tools/blob/master/ge2maintainer.sh
Thanks Andy and Bart.
On Mon, Nov 18, 2024 at 6:05 PM Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Mon, Nov 18, 2024 at 12:00:00PM +0100, Bartosz Golaszewski wrote:
On Tue, Nov 12, 2024 at 5:09 PM Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Tue, Nov 05, 2024 at 04:39:38PM +0200, Andy Shevchenko wrote:
On Tue, Nov 05, 2024 at 12:45:23PM +0530, Sai Kumar Cholleti wrote:
...
Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Does this need to be applied, Bart? Seems it is missed in your branches...
Maybe if the author used get_maintainers.pl as they should, I would have noticed this earlier?
Ah good catch!
Sai, FYI, I use my script [1] which does all required stuff for me. Feel free to use it, patch, comment, etc...
I have some other fixes to pick up so I'll send this later in the merge window.
Thanks!
-- With Best Regards, Andy Shevchenko
From: Bartosz Golaszewski bartosz.golaszewski@linaro.org
On Tue, 05 Nov 2024 12:45:23 +0530, Sai Kumar Cholleti wrote:
Setting GPIO direction = high, sometimes results in GPIO value = 0.
If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1:
$ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0
[...]
Applied, thanks!
[1/1] gpio: exar: set value when external pull-up or pull-down is present commit: 72cef64180de04a7b055b4773c138d78f4ebdb77
Best regards,
linux-stable-mirror@lists.linaro.org
-
Andy Shevchenko -
Bartosz Golaszewski -
sai kumar -
Sai Kumar Cholleti