linux-kernel - Re: [PATCH 1/9] pinctrl: sunxi: Support I/O bias voltage setting on A80

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Message-ID: <CACRpkdZFwG9-ap3jMe+eGDCgzG9+fKRXVEb4Q=pWasd5GUs9tQ@mail.gmail.com>
Date:   Mon, 11 Feb 2019 09:20:52 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH 1/9] pinctrl: sunxi: Support I/O bias voltage setting on A80

On Wed, Feb 6, 2019 at 4:32 AM Chen-Yu Tsai <wens@...e.org> wrote:

> The A80 SoC has configuration registers for I/O bias voltage. Incorrect
> settings would make the affected peripherals inoperable in some cases,
> such as Ethernet RGMII signals biased at 2.5V with the settings still
> at 3.3V. However low speed signals such as MDIO on the same group of
> pins seem to be unaffected.
>
> Previously there was no way to know what the actual voltage used was,
> short of hard-coding a value in the device tree. With the new pin bank
> regulator supply support in place, the driver can now query the
> regulator for its voltage, and if it's valid (as opposed to being the
> dummy regulator), set the bias voltage setting accordingly.
>
> Add a quirk to denote the presence of the configuration registers, and
> a function to set the correct setting based on the voltage read back
> from the regulator.
>
> This is only done when the regulator is first acquired and enabled.
> While it would be nice to have a notifier on the regulator so that when
> the voltage changes, the driver can update the setting, in practice no
> board currently supports dynamic changing of the I/O voltages.
>
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>

I merged the v5.0-rc6 into my devel branch and applied this patch on
top now.

All the DTS file changes should be merged through ARM SoC, and
they should work fine now.

Yours,
Linus Walleij