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SubjectRe: [PATCH] power: supply: core: Ignore -EIO for uevent
Hi,

On Wed, Aug 24, 2022 at 04:57:20PM -0700, Brian Norris wrote:
> For uevents, we enumerate all properties. Some battery implementations
> don't implement all standard properties, and may return -EIO for
> properties that aren't recognized. This means we never report uevents
> for such batteries.
>
> It's better to ignore these errors and skip the property, as we do with
> ENODATA and ENODEV.
>
> Example battery implementation: Acer Chromebook Tab 10 (a.k.a. Google
> Gru-Scarlet) has a virtual "SBS" battery implementation in its Embedded
> Controller on top of an otherwise non-SBS battery.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---

-EIO means input/output error. If a driver is reporting that for an
unimplemented feature it's a bug that should be fixed in the driver.
Handling it here means userspace ABI changes for temporary issues.

-- Sebastian

> drivers/power/supply/power_supply_sysfs.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index 4239591e1522..36fce572a213 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -439,10 +439,12 @@ static int add_prop_uevent(struct device *dev, struct kobj_uevent_env *env,
> dev_attr = &pwr_attr->dev_attr;
>
> ret = power_supply_show_property(dev, dev_attr, prop_buf);
> - if (ret == -ENODEV || ret == -ENODATA) {
> + if (ret == -ENODEV || ret == -ENODATA || ret == -EIO) {
> /*
> * When a battery is absent, we expect -ENODEV. Don't abort;
> - * send the uevent with at least the the PRESENT=0 property
> + * send the uevent with at least the PRESENT=0 property. Some
> + * batteries also report EIO, even for some standard
> + * properties.
> */
> return 0;
> }
> --
> 2.37.2.672.g94769d06f0-goog
>
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