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From:   Alison Wang <alison.wang@nxp.com>
To:     Shawn Guo <shawnguo@kernel.org>, Michael Walle <michael@walle.cc>
CC:     "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Leo Li <leoyang.li@nxp.com>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>
Subject: RE: [EXT] Re: [PATCH] arm64: dts: ls1028a: put SAIs into async mode
Thread-Topic: [EXT] Re: [PATCH] arm64: dts: ls1028a: put SAIs into async mode
Thread-Index: AQHVrnBLtaYchIru+E6aNXw66ImuFqeyq8zw
Date:   Tue, 10 Dec 2019 05:35:27 +0000
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References: <20191129210937.26808-1-michael@walle.cc>
 <20191209090840.GL3365@dragon>
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Hi, Michael,

In most of our cases, TX and RX are using the same BCLK and SYNC clocks. So=
 the default synchronous mode (sync Rx with Tx) is used, which means both t=
ransmitter and receiver will send and receive data by following clocks of t=
ransmitter. It is verified on our boards.


Best Regards,
Alison Wang

> -----Original Message-----
> From: Shawn Guo <shawnguo@kernel.org>
> Sent: Monday, December 9, 2019 5:09 PM
> To: Michael Walle <michael@walle.cc>; Alison Wang <alison.wang@nxp.com>
> Cc: linux-arm-kernel@lists.infradead.org; devicetree@vger.kernel.org;
> linux-kernel@vger.kernel.org; Leo Li <leoyang.li@nxp.com>; Rob Herring
> <robh+dt@kernel.org>; Mark Rutland <mark.rutland@arm.com>
> Subject: [EXT] Re: [PATCH] arm64: dts: ls1028a: put SAIs into async mode
>=20
> Caution: EXT Email
>=20
> + Alison Wang
>=20
> On Fri, Nov 29, 2019 at 10:09:37PM +0100, Michael Walle wrote:
> > The LS1028A SoC has only unidirectional SAIs. Therefore, it doesn't
> > make sense to have the RX and TX part synchronous. Even worse, the RX
> > part wont work out of the box because by default it is configured as
> > synchronous to the TX part. And as said before, the pinmux of the SoC
> > can only be configured to route either the RX or the TX signals to the
> > SAI but never both at the same time. Thus configure the asynchronous
> > mode by default.
> >
> > Signed-off-by: Michael Walle <michael@walle.cc>
>=20
> Alison, Leo,
>=20
> Looks good to you?
>=20
> Shawn
>=20
> > ---
> >  arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi
> > b/arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi
> > index 379913756e90..9be33426e5ce 100644
> > --- a/arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi
> > @@ -637,6 +637,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 4>,
> >                              <&edma0 1 3>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > @@ -651,6 +652,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 6>,
> >                              <&edma0 1 5>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > @@ -665,6 +667,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 8>,
> >                              <&edma0 1 7>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > @@ -679,6 +682,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 10>,
> >                              <&edma0 1 9>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > @@ -693,6 +697,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 12>,
> >                              <&edma0 1 11>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > @@ -707,6 +712,7 @@
> >                       dma-names =3D "tx", "rx";
> >                       dmas =3D <&edma0 1 14>,
> >                              <&edma0 1 13>;
> > +                     fsl,sai-asynchronous;
> >                       status =3D "disabled";
> >               };
> >
> > --
> > 2.20.1
> >