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From:   Chen-Yu Tsai <wens@csie.org>
Date:   Wed, 28 Aug 2019 21:46:43 +0800
Message-ID: <CAGb2v67hS1a2iNJYgc97vwpg6hZwxjoxRhdMb5PjHmMrOC1jNA@mail.gmail.com>
Subject: Re: [linux-sunxi] Re: [PATCH] mmc: sunxi: fix unusuable eMMC on some
 H6 boards by disabling DDR
To:     Maxime Ripard <mripard@kernel.org>
Cc:     =?UTF-8?Q?Alejandro_Gonz=C3=A1lez?= 
        <alejandro.gonzalez.correo@gmail.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>
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On Wed, Aug 28, 2019 at 9:43 PM Maxime Ripard <mripard@kernel.org> wrote:
>
> On Wed, Aug 28, 2019 at 09:29:32PM +0800, Chen-Yu Tsai wrote:
> > On Wed, Aug 28, 2019 at 8:52 PM Linus Walleij <linus.walleij@linaro.org> wrote:
> > >
> > > On Sun, Aug 25, 2019 at 5:06 PM Alejandro González
> > > <alejandro.gonzalez.correo@gmail.com> wrote:
> > >
> > > > Jernej Skrabec compared the BSP driver with this
> > > > driver, and found that the BSP driver configures pinctrl to operate at
> > > > 1.8 V when entering DDR mode (although 3.3 V operation is supported), while
> > > > the mainline kernel lacks any mechanism to switch voltages dynamically.
> >
> > AFAIK The Pine H64 does not have the ability to switch I/O voltages. It is
> > fixed to either 1.8V (the default based on the schematics) or 3.3V.
>
> Should that be handled at the board level then maybe?

Yeah. You'd specify which one using vqmmc-supply in the mmc node and
vcc-pc-supply
in the pinctrl node.

ChenYu