From: Brian Norris <briannorris@chromium.org>
To: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Caesar Wang <wxt@rock-chips.com>, Jiri Kosina <jikos@kernel.org>,
linux-rockchip@lists.infradead.org, dbasehore@chromium.org,
Douglas Anderson <dianders@chromium.org>,
Heiko Stuebner <heiko@sntech.de>,
linux-input@vger.kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Dmitry Torokhov <dtor@chromium.org>,
Benson Leung <bleung@chromium.org>,
Guohua Zhong <ghzhong@yifangdigital.com>,
"Zhonghui\"" <zhonghui.fu@linux.intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] HID: i2c-hid: support the regulator
Date: Wed, 14 Sep 2016 16:02:42 +0800 [thread overview]
Message-ID: <20160914080241.GA14576@localhost> (raw)
In-Reply-To: <20160914075505.GA14271@localhost>
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.
Brian
next prev parent reply other threads:[~2016-09-14 8:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-04 22:11 [PATCH 1/2] dt-bindings: add the regulator optional properties Caesar Wang
2016-09-04 22:11 ` Caesar Wang
2016-09-04 22:11 ` [PATCH 2/2] HID: i2c-hid: support the regulator Caesar Wang
2016-09-04 22:11 ` Caesar Wang
2016-09-14 7:36 ` Benjamin Tissoires
2016-09-14 7:55 ` Brian Norris
2016-09-14 7:55 ` Brian Norris
2016-09-14 8:02 ` Brian Norris [this message]
2016-09-14 14:31 ` Benjamin Tissoires
2016-09-12 16:16 ` [PATCH 1/2] dt-bindings: add the regulator optional properties Rob Herring
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