On Wed, Oct 25, 2017 at 03:34:16PM +1030, Andrew Jeffery wrote:
> Reset tolerance is added to gpiolib with the introduction of a new
> pinconf parameter propagating the request to hardware. The existing
> persistence support for sleep is augmented to include reset tolerance
> if the GPIO driver provides it. Persistence continues to be enabled by
> default; in-kernel consumers can opt out, but userspace (currently) does
> not have a choice.
>
> The *_SLEEP_MAY_LOSE_VALUE and *_SLEEP_MAINTAIN_VALUE symbols are
> renamed, dropping the SLEEP prefix to reflect that the concept is no
> longer sleep-specific. I feel that renaming to just *_MAY_LOSE_VALUE
> could initially be misinterpreted, so I've further changed the symbols
> to *_TRANSITORY and *_PERSISTENT to address this.
>
> The sysfs interface is modified only to keep consistency with the
> chardev interface in enforcing persistence for userspace exports.
>
> Signed-off-by: Andrew Jeffery <and...@aj.id.au>
> ---
> I'm not wedded to the names 'transitory' and 'persistent', so feel free to
> paint the bikeshed some other colour.
>
I am happy enough with the names.
> drivers/gpio/gpiolib-of.c | 6 ++--
> drivers/gpio/gpiolib-sysfs.c | 14 +++++---
> drivers/gpio/gpiolib.c | 58
> ++++++++++++++++++++++++++++++---
> drivers/gpio/gpiolib.h | 2 +-
> include/dt-bindings/gpio/gpio.h | 6 ++--
> include/linux/gpio/consumer.h | 8 +++++
> include/linux/gpio/machine.h | 4 +--
> include/linux/of_gpio.h | 2 +-
> include/linux/pinctrl/pinconf-generic.h | 2 ++
> 9 files changed, 84 insertions(+), 18 deletions(-)
> @@ -2424,6 +2428,46 @@ int gpiod_set_debounce(struct gpio_desc *desc,
> unsigned debounce)
> EXPORT_SYMBOL_GPL(gpiod_set_debounce);
>
> /**
> + * gpiod_set_transitory - Lose or retain GPIO state on suspend or reset
> + * @desc: descriptor of the GPIO for which to configure persistence
> + * @transitory: True to lose state on suspend or reset, false for persistence
> + *
> + * Returns:
> + * 0 on success, otherwise a negative error code.
> + */
> +int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)
> +{
> + struct gpio_chip *chip;
> + unsigned long packed;
> + int gpio;
> + int rc;
> +
> + /* Handle FLAG_TRANSITORY first for suspend case */
> + if (transitory)
> + set_bit(FLAG_TRANSITORY, &desc->flags);
> + else
> + clear_bit(FLAG_TRANSITORY, &desc->flags);
> +
> + /* Configure reset persistence if the controller supports it */
> + chip = desc->gdev->chip;
> + if (!chip->set_config)
> + return 0;
> +
> + packed = pinconf_to_config_packed(PIN_CONFIG_RESET_TOLERANT,
> + !transitory);
> + gpio = gpio_chip_hwgpio(desc);
> + rc = chip->set_config(chip, gpio, packed);
> + if (rc == -ENOTSUPP) {
> + dev_dbg(&desc->gdev->dev, "Reset tolerance not supported for
> GPIO %d\n",
> + gpio);
> + return 0;
> + }
> +
> + return rc;
This means that if we have a set_config we are directly
equating PERSISTENT to RESET_TOLERANT, which seems wrong to
me. I might have a GPIO on a controller with pinconf that
doesn't have anything to do with RESET_TOLERANT. Should the
PIN_CONFIG_RESET_TOLERANT, really just be PIN_CONFIG_PERSISTENT?
And then its upto the driver what persistence means for that
chip?
Thanks,
Charles
