linux-kernel - Re: [PATCH 3/4] ARM: dts: sun8i-a83t-tbs-a711: Add support for the vibrator motor

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Message-ID: <20200224141437.opcsfhozfppulu4g@core.my.home>
Date:   Mon, 24 Feb 2020 15:14:37 +0100
From:   Ondřej Jirman <megous@...ous.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     linux-sunxi@...glegroups.com,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Mark Rutland <mark.rutland@....com>,
        Luca Weiss <luca@...tu.xyz>, Tomas Novotny <tomas@...otny.cz>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/4] ARM: dts: sun8i-a83t-tbs-a711: Add support for the
 vibrator motor

Hello,

On Mon, Feb 24, 2020 at 10:10:59AM +0100, Maxime Ripard wrote:
> Hi,
> 
> On Sun, Feb 23, 2020 at 12:14:27AM +0100, Ondrej Jirman wrote:
> > The board has a vibrator mottor. Hook it to the input subsystem.
> >
> > Signed-off-by: Ondrej Jirman <megous@...ous.com>
> > ---
> >  arch/arm/boot/dts/sun8i-a83t-tbs-a711.dts | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/sun8i-a83t-tbs-a711.dts b/arch/arm/boot/dts/sun8i-a83t-tbs-a711.dts
> > index 2fd31a0a0b344..a22920275e99b 100644
> > --- a/arch/arm/boot/dts/sun8i-a83t-tbs-a711.dts
> > +++ b/arch/arm/boot/dts/sun8i-a83t-tbs-a711.dts
> > @@ -99,6 +99,11 @@ panel_input: endpoint {
> >  		};
> >  	};
> >
> > +	vibrator {
> > +		compatible = "gpio-vibrator";
> > +		vcc-supply = <&reg_ldo_io1>;
> > +	};
> > +
> 
> LDO IO1 can also be muxed in as a GPIO iirc, why did you choose the
> regulator instead?

According to the specification, LDO needs to be enabled (value 0b11)
to achieve the specified max driving current of 150mA:

  https://megous.com/dl/tmp/92b7d9d94820c3ba.png

Otherwise the chip is probably just using the regular CMOS logic output
(typically limited to around 20-35mA, but not specified in this datasheet),
which would be probably overdriven, if we try to drive the motor with it.

And since we're driving a motor directly, the more the better.

thank you and regards,
	o.

> Maxime