From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH V4 9/9] pwm_bl: Add mandatory backlight enable regulator Date: Wed, 20 Mar 2013 12:00:10 -0600 Message-ID: <5149F92A.3070004@wwwdotorg.org> References: <1363719573-20926-1-git-send-email-achew@nvidia.com> <1363719573-20926-10-git-send-email-achew@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1363719573-20926-10-git-send-email-achew-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Chew Cc: romain.naour-oid7hba3+9NWj0EZb7rXcA@public.gmane.org, kgene.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, drwyrm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, stefan-WB6LKoYH/xlAfugRpC6u6w@public.gmane.org, laforge-WB6LKoYH/xlAfugRpC6u6w@public.gmane.org, philipp.zabel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, lost.distance-/E1597aS9LQAvxtiuMwx3w@public.gmane.org, marek.vasut-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, robert.jarzmik-GANU6spQydw@public.gmane.org, eric.y.miao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, haojian.zhuang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, gxt-TG0Ac1+ktVePQbnJrJN+5g@public.gmane.org, shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, linux-ci5G2KO2hbZ+pU9mqzGVBQ@public.gmane.org, thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org, acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, openezx-devel-ZwoEplunGu3n3BO9LpVK+9i2O/JbrIOy@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 03/19/2013 12:59 PM, Andrew Chew wrote: > Many backlights need to be explicitly enabled. Typically, this is done > with a GPIO. For flexibility, we generalize the enable mechanism to a > regulator. > > If an enable regulator is not needed, then a dummy regulator can be given > to the backlight driver. If a GPIO is used to enable the backlight, > then a fixed regulator can be instantiated to control the GPIO. > > The backlight enable regulator can be specified in the device tree node > for the backlight, or can be done with legacy board setup code in the > usual way. > diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > index 1e4fc72..7e2e089 100644 > --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > @@ -10,6 +10,11 @@ Required properties: > last value in the array represents a 100% duty cycle (brightest). > - default-brightness-level: the default brightness level (index into the > array defined by the "brightness-levels" property) > + - enable-supply: A phandle to the regulator device tree node. This > + regulator will be turned on and off as the pwm is enabled and disabled. > + Many backlights are enabled via a GPIO. In this case, we instantiate > + a fixed regulator and give that to enable-supply. If a regulator > + is not needed, then provide a dummy fixed regulator. "enable" doesn't seem like the right name here; if this really is an "enable" input, then it's not a regulator. If you're calling it "enable" because the regulator is usually controlled by a GPIO that enables it, then what you really have is a regulator that provides power to the backlight, and the method that you enable that regulator is irrelevant. Put another way, wouldn't "power" be a better name, thus making the property "power-supply"? Although that property name migth be considered to have some negative correlation with other concepts, so if people object to that, perhaps e.g. "vdd-supply"?