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SubjectRe: [PATCH v4 1/2] gpio: gpiolib: Generalise state persistence beyond sleep
On Thu, Nov 30, 2017 at 4:55 AM, Andrew Jeffery <andrew@aj.id.au> 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@aj.id.au>
> Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> Acked-by: Rob Herring <robh@kernel.org>

Nice work, patch applied!

> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 3f454eaf2101..0bd472ffb072 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -474,11 +474,15 @@ static ssize_t export_store(struct class *class,
> status = -ENODEV;
> goto done;
> }
> - status = gpiod_export(desc, true);
> - if (status < 0)
> - gpiod_free(desc);
> - else
> - set_bit(FLAG_SYSFS, &desc->flags);
> +
> + status = gpiod_set_transitory(desc, false);
> + if (!status) {
> + status = gpiod_export(desc, true);
> + if (status < 0)
> + gpiod_free(desc);
> + else
> + set_bit(FLAG_SYSFS, &desc->flags);
> + }

Part of me just wanna drop this hunk of the patch and let
the old sysfs ABI rot.

But I guess that is especially malevolent so I will abstain.


Yours,
Linus Walleij

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