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From:   Viorel Suman <viorel.suman@nxp.com>
To:     Mark Brown <broonie@kernel.org>,
        "Viorel Suman (OSS)" <viorel.suman@oss.nxp.com>
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        "S.j. Wang" <shengjiu.wang@nxp.com>,
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Subject: RE: [RFC PATCH] ASoC: ak4458: use reset control instead of reset gpio
Thread-Topic: [RFC PATCH] ASoC: ak4458: use reset control instead of reset
 gpio
Thread-Index: AQHWvGa/ULTQkQTG3EuXXoMLDy7cbKnMmESAgAAFAkA=
Date:   Tue, 17 Nov 2020 18:17:36 +0000
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References: <20201116222036.343635-1-viorel.suman@oss.nxp.com>
 <20201117173901.GH5142@sirena.org.uk>
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> On Tue, Nov 17, 2020 at 12:20:36AM +0200, Viorel Suman (OSS) wrote:
>=20
> >  static void ak4458_power_off(struct ak4458_priv *ak4458)  {
> > -	if (ak4458->reset_gpiod) {
> > -		gpiod_set_value_cansleep(ak4458->reset_gpiod, 0);
> > -		usleep_range(1000, 2000);
> > +	if (ak4458->reset) {
> > +		reset_control_assert(ak4458->reset);
> > +		msleep(20);
>=20
> We should really leave the support for doing this via GPIO in place for b=
ackwards
> compatibility I think, we could mark it as deprecated in the binding docu=
ment.
> Otherwise this makes sense to me and solves a real problem we have with t=
he
> handling of resets so we should look into doing this for new bindings.
>=20
> One thing I'm not clear on is if there's some way to ensure that we don't=
 have
> different instances of the device resetting each other without them notic=
ing?
> Shouldn't be an issue in practice for the use here.

The way to ensure that we don't have different instances of the device rese=
tting each
other is to rely on the way the "shared" reset is handled by reset API:=20
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
+	ak4458->reset =3D devm_reset_control_get_optional_shared(ak4458->dev, NUL=
L);
+	if (IS_ERR(ak4458->reset))
+		return PTR_ERR(ak4458->reset);
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

/Viorel