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Date:   Thu, 8 Oct 2020 17:10:22 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     =?utf-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Cc:     Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] arm64: dts: allwinner: h6: add eMMC voltage property
 for Beelink GS1
Message-ID: <20201008151022.ryhijbj42y7kgzvb@gilmour.lan>
References: <20201003092001.405238-1-peron.clem@gmail.com>
 <20201005092145.wdu4m4pwxydv76ou@gilmour.lan>
 <CAJiuCcfydz4GS3fUTampBLkDC4f6xVWmRpSRJ55TiDStdRCFmA@mail.gmail.com>
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Hi Cl=E9ment,

On Mon, Oct 05, 2020 at 08:47:19PM +0200, Cl=E9ment P=E9ron wrote:
> On Mon, 5 Oct 2020 at 11:21, Maxime Ripard <maxime@cerno.tech> wrote:
> >
> > Hi Cl=E9ment,
> >
> > On Sat, Oct 03, 2020 at 11:20:01AM +0200, Cl=E9ment P=E9ron wrote:
> > > Sunxi MMC driver can't distinguish at runtime what's the I/O voltage
> > > for HS200 mode.
> >
> > Unfortunately, that's not true (or at least, that's not related to your=
 patch).
> >
> > > Add a property in the device-tree to notify MMC core about this
> > > configuration.
> > >
> > > Fixes: 089bee8dd119 ("arm64: dts: allwinner: h6: Introduce Beelink GS=
1 board")
> > > Signed-off-by: Cl=E9ment P=E9ron <peron.clem@gmail.com>
> > > ---
> > >  arch/arm64/boot/dts/allwinner/sun50i-h6-beelink-gs1.dts | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-beelink-gs1.dts =
b/arch/arm64/boot/dts/allwinner/sun50i-h6-beelink-gs1.dts
> > > index 049c21718846..3f20d2c9bbbb 100644
> > > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-beelink-gs1.dts
> > > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-beelink-gs1.dts
> > > @@ -145,6 +145,7 @@ &mmc2 {
> > >       vqmmc-supply =3D <&reg_bldo2>;
> > >       non-removable;
> > >       cap-mmc-hw-reset;
> > > +     mmc-hs200-1_8v;
> > >       bus-width =3D <8>;
> > >       status =3D "okay";
> > >  };
> >
> > I'm not really sure what you're trying to fix here, but as far as MMC
> > goes, eMMC's can support io voltage of 3.3, 1.8 and 1.2V. Modes up until
> > HS DDR (50MHz in DDR) will use an IO voltage of 3.3V, higher speed modes
> > (HS200 and HS400) supporting 1.8V and 1.2V.
>=20
> Some users report that the eMMC is not working properly on their
> Beelink GS1 boards.
>=20
> > The mmc-hs200-1_8v property states that the MMC controller supports the
> > HS200 mode at 1.8V. Now, I can only assume that since BLDO2 is set up at
> > 1.8V then otherwise, the MMC core will rightfully decide to use the
> > highest supported mode. In this case, since the driver sets it, it would
> > be HS-DDR at 3.3V, which won't work with that fixed regulator.
> >
> > I can only assume that enabling HS200 at 1.8V only fixes the issue you
> > have because otherwise it would use HS-DDR at 3.3V, ie not actually
> > fixing the issue but sweeping it under the rug.
> >
> > Trying to add mmc-ddr-1_8v would be a good idea
>=20
> Thanks for the explanation, this is indeed the correct one.
> So It looks like the SDIO controller has an issue on some boards when
> using HS-DDR mode.
>=20
> Is this patch acceptable with the proper commit log?

If HS-DDR works, yes, but I assume it doesn't?

Maxime

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