linux-kernel - Re: [PATCH v2 2/4] [media] ad5820: Add support for enable pin

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Date:   Thu, 20 Sep 2018 21:12:44 +0200
From:   Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Sakari Ailus <sakari.ailus@....fi>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH v2 2/4] [media] ad5820: Add support for enable pin

On Thu, Sep 20, 2018 at 9:08 PM Pavel Machek <pavel@....cz> wrote:
>
> On Thu 2018-09-20 21:06:16, Ricardo Ribalda Delgado wrote:
> > Hi Pavel
> >
> > On Thu, Sep 20, 2018 at 8:54 PM Pavel Machek <pavel@....cz> wrote:
> > >
> > > On Thu 2018-09-20 20:45:52, Ricardo Ribalda Delgado wrote:
> > > > This patch adds support for a programmable enable pin. It can be used in
> > > > situations where the ANA-vcc is not configurable (dummy-regulator), or
> > > > just to have a more fine control of the power saving.
> > > >
> > > > The use of the enable pin is optional.
> > > >
> > > > Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
> > >
> > > Do we really want to do that?
> > >
> > > Would it make more sense to add gpio-regulator and connect ad5820 to
> > > it in such case?
> > >
> >
> > My board (based on db820c)  has both:
> >
> > ad5820: dac@0c {
> >    compatible = "adi,ad5820";
> >    reg = <0x0c>;
> >
> >    VANA-supply = <&pm8994_l23>;
> >    enable-gpios = <&msmgpio 26 GPIO_ACTIVE_HIGH>;
> > };
>
> Well, I'm sure you could have gpio-based regulator powered from
> pm8994_l23, and outputting to ad5820.
>
> Does ad5820 chip have a gpio input for enable?

xshutdown pin:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5821.pdf

(AD5820,AD5821, and AD5823 are compatibles, or at least that is waht
the module manufacturer says :)


>                                                                         Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html



--
Ricardo Ribalda