linux-kernel - Re: [PATCH 2/2] arm64: dts: berlin4ct: enable all i2c nodes for the STB board

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Message-ID: <20151123161713.509b3294@xhacker>
Date:	Mon, 23 Nov 2015 16:17:13 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
CC:	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<catalin.marinas@....com>, <will.deacon@....com>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] arm64: dts: berlin4ct: enable all i2c nodes for the
 STB board

On Mon, 23 Nov 2015 09:12:18 +0100
Sebastian Hesselbarth <sebastian.hesselbarth@...il.com> wrote:

> On 23.11.2015 03:49, Jisheng Zhang wrote:
> > On Fri, 20 Nov 2015 22:19:32 +0100
> > Sebastian Hesselbarth wrote:  
> >> On 20.11.2015 10:47, Jisheng Zhang wrote:  
> >>> Enable all i2c nodes for the Marvell berlin BG4CT STB board.
> >>>
> >>> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> >>> ---
> >>>   arch/arm64/boot/dts/marvell/berlin4ct-stb.dts | 50 +++++++++++++++++++++++++++
> >>>   1 file changed, 50 insertions(+)
> >>>
> >>> diff --git a/arch/arm64/boot/dts/marvell/berlin4ct-stb.dts b/arch/arm64/boot/dts/marvell/berlin4ct-stb.dts
> >>> index 348c37e..9e8e2e0 100644
> >>> --- a/arch/arm64/boot/dts/marvell/berlin4ct-stb.dts
> >>> +++ b/arch/arm64/boot/dts/marvell/berlin4ct-stb.dts
> >>> @@ -61,6 +61,56 @@
> >>>   	};
> >>>   };
> >>>
> >>> +&avio_pinctrl {
> >>> +	twsi1_pmux: twsi1-pmux {
> >>> +		groups = "TX_EDDC_SCL", "TX_EDDC_SDA";
> >>> +		function = "tx_eddc";
> >>> +	};  
> >>
> >> Please keep the pinmux sub-nodes in the SoC dtsi as long
> >> as they are not strictly board specific, i.e. gpios.  
> >
> > Hmm, seems all boards configure this pin for EDDC usage, so it's fine
> > to move to soc
> >  
> >>  
> >>> +};
> >>> +
> >>> +&i2c0 {
> >>> +	status = "okay";
> >>> +	pinctrl-0 = <&twsi0_pmux>;
> >>> +	pinctrl-names = "default";  
> >>
> >> If there is only one (or a default) pinctrl-0 option for i2c0,
> >> you can also move it to the SoC dtsi.  
> >
> > Some board may not use i2c0, i2c2, i2c3 host and use the pin as gpio for other
> > purpose. Considering the above twsi1_pmux usage, what's the better solution?
> > move twsi1_pmux to soc's dtsi and leave i2c0, i2c2, i2c3 pinctrl in board dts?  
> 
> If some boards don't use i2cN, they do not enable the node in their
> board dts. That is sufficient to not configure the pinmux as it will
> only be set if a driver is loaded for that node.
> 
> If there is only one or two different pinmux settings for a specific
> function _always_ move the pinmux setting into SoC dtsi. If there is
> a well known default out of two or more possible settings, we may also
> have that pinmux as a default in the i2c node and only overwrite it
> when we have a board that uses a different setting.

Got it. Thanks for the detailed explanations.

> 
> So, for i2c: Move all pinctrl/pinctrl-names properties to the SoC
> dtsi.

Will do in v2 when clk stuff is accepted.

Thanks,
Jisheng
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