[PATCH 2/2] HID: i2c-hid: support the regulator

Brian Norris briannorris at chromium.org
Wed Sep 14 01:02:42 PDT 2016

On Wed, Sep 14, 2016 at 03:55:05PM +0800, Brian Norris wrote:
> The default behavior of regulator_get() is to provide a dummy regulator
> if none is found. So the pointer is never NULL, and it won't break
> devices without a regulator. If you don't want a dummy regulator you
> would use regulator_get_optional() instead, and you would then need to
> handle ERR_PTR(-ENODEV) specifically.

One caveat to the never-NULL comment above that I just noticed:

If CONFIG_REGULATOR=n, then regulator_get() actually returns NULL (see
include/linux/regulator/consumer.h), but it also specifically has a
comment right next to that NULL return, saying:

        /* Nothing except the stubbed out regulator API should be
         * looking at the value except to check if it is an error
         * value. Drivers are free to handle NULL specifically by
         * skipping all regulator API calls, but they don't have to.
         * Drivers which don't, should make sure they properly handle
         * corner cases of the API, such as regulator_get_voltage()
         * returning 0.

So, we still don't need to handle the NULL case specially.


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