On Mon, Oct 30, 2017 at 04:52:17PM +1030, Andrew Jeffery wrote:
> General support for state persistence is added to gpiolib with the
> introduction of a new pinconf parameter to propagate the request to
> hardware. The existing persistence support for sleep is adapted to
> include hardware support 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 <andrew@xxxxxxxx>
> ---
> /**
> + * 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 */
This comment could use an update.
> + chip = desc->gdev->chip;
> + if (!chip->set_config)
> + return 0;
> +
> + packed = pinconf_to_config_packed(PIN_CONFIG_PERSIST_STATE,
> + !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);
And this debug message.
> + return 0;
> + }
> +
> + return rc;
> +}
> +EXPORT_SYMBOL_GPL(gpiod_set_transitory);
> +
Otherwise think this all looks good to me.
Thanks,
Charles
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