netdev - Re: [PATCH 07/12] arm64: dts: allwinner: orange-pi-3: Enable ethernet

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Message-ID: <20190408232232.fsl2ddthwo2rr4ql@core.my.home>
Date:   Tue, 9 Apr 2019 01:22:32 +0200
From:   Ondřej Jirman <megous@...ous.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     linux-sunxi@...glegroups.com, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Mark Rutland <mark.rutland@....com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Arend van Spriel <arend.vanspriel@...adcom.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Naveen Gupta <naveen.gupta@...ress.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, linux-gpio@...r.kernel.org
Subject: Re: [PATCH 07/12] arm64: dts: allwinner: orange-pi-3: Enable ethernet

On Mon, Apr 08, 2019 at 09:40:42AM +0200, Maxime Ripard wrote:
> On Sat, Apr 06, 2019 at 01:45:09AM +0200, megous@...ous.com wrote:
> > From: Ondrej Jirman <megous@...ous.com>
> >
> > Orange Pi 3 has two regulators that power the Realtek RTL8211E.
> > According to the phy datasheet, both regulators need to be enabled
> > at the same time, but we can only specify a single phy-supply in
> > the DT.
> >
> > This can be achieved by making one regulator depedning on the
> > other via vin-supply. While it's not a technically correct
> > description of the hardware, it achieves the purpose.
> >
> > All values of RX/TX delay were tested exhaustively and a middle
> > one of the working values was chosen.
> >
> > Signed-off-by: Ondrej Jirman <megous@...ous.com>
> > ---
> >  .../dts/allwinner/sun50i-h6-orangepi-3.dts    | 44 +++++++++++++++++++
> >  1 file changed, 44 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-3.dts b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-3.dts
> > index 644946749088..5270142527f5 100644
> > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-3.dts
> > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-3.dts
> > @@ -15,6 +15,7 @@
> >
> >  	aliases {
> >  		serial0 = &uart0;
> > +		ethernet0 = &emac;
> >  	};
> >
> >  	chosen {
> > @@ -64,6 +65,27 @@
> >  		regulator-max-microvolt = <5000000>;
> >  		regulator-always-on;
> >  	};
> > +
> > +	/*
> > +	 * The board uses 2.5V RGMII signalling. Power sequence
> > +	 * to enable the phy is to enable GMAC-2V5 and GMAC-3V3 (aldo2)
> > +	 * power rails at the same time and to wait 100ms.
> > +	 */
> > +	reg_gmac_2v5: gmac-2v5 {
> > +                compatible = "regulator-fixed";
> > +                regulator-name = "gmac-2v5";
> > +                regulator-min-microvolt = <2500000>;
> > +                regulator-max-microvolt = <2500000>;
> > +                startup-delay-us = <100000>;
> > +                enable-active-high;
> > +                gpio = <&pio 3 6 GPIO_ACTIVE_HIGH>; /* PD6 */
> 
> Is enable-active-high still needed? It's redundant with the
> GPIO_ACTIVE_HIGH flag.

Looking at the code, use/non-use of enable-active-high inhibits
flags specified in gpio property. So the GPIO_ACTIVE_HIGH flag
is ignored here (had GPIO_ACTIVE_LOW been used, the kernel would
ignore it too and print a warning).

So enable-active-high is still necessary here.

See comment in gpiolib-of.c where this is handled:

/*
 * The regulator GPIO handles are specified such that the
 * presence or absence of "enable-active-high" solely controls
 * the polarity of the GPIO line. Any phandle flags must
 * be actively ignored.
 */

regards,
	o.

> The indentation is wrong here as well.
> 
> Maxime
> 
> --
> Maxime Ripard, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com