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

On Sep 14 2016 or thereabouts, Brian Norris wrote:

On Wed, Sep 14, 2016 at 03:55:05PM +0800, Brian Norris wrote:

quoted

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.

Well, all the other regulator calls are either regulator_enable() or
regulator_disable(), which in this case (CONFIG_REGULATOR=n) are
returning 0.

So I think the whole patch is safe in its current form. Thanks for the
explanations.

Acked-by: Benjamin Tissoires <redacted>

Cheers,
Benjamin

Brian