linux-kernel - Aw: Re: [RFC v1 5/5] arm64: dts: mediatek: Add mt7986 based Bananapi R3 Mini

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Date: Wed, 8 May 2024 20:25:32 +0200
From: Frank Wunderlich <frank-w@...lic-files.de>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: Frank Wunderlich <linux@...web.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
 <conor+dt@...nel.org>, Michael Turquette <mturquette@...libre.com>, Stephen
 Boyd <sboyd@...nel.org>, Pavel Machek <pavel@....cz>, Lee Jones
 <lee@...nel.org>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
 <pabeni@...hat.com>, Matthias Brugger <matthias.bgg@...il.com>, Eric
 Woudstra <ericwouds@...il.com>, Tianling Shen <cnsztl@...ortalwrt.org>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-clk@...r.kernel.org, linux-leds@...r.kernel.org,
 netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org, Tianling Shen <cnsztl@...il.com>
Subject: Aw: Re: [RFC v1 5/5] arm64: dts: mediatek: Add mt7986 based
 Bananapi R3 Mini

Hi

> Gesendet: Dienstag, 07. Mai 2024 um 15:35 Uhr
> Von: "AngeloGioacchino Del Regno" <angelogioacchino.delregno@...labora.com>
>
> Il 06/05/24 18:00, Frank Wunderlich ha scritto:

> >>> +	fan: pwm-fan {
> >>> +		compatible = "pwm-fan";
> >>> +		#cooling-cells = <2>;
> >>> +		/* cooling level (0, 1, 2) - pwm inverted */
> >>> +		cooling-levels = <255 96 0>;
> >>
> >> Did you try to actually invert the PWM?
> >>
> >> Look for PWM_POLARITY_INVERTED ;-)
> >
> > Mtk pwm driver does not support it
> >
> > https://elixir.bootlin.com/linux/latest/source/drivers/pwm/pwm-mediatek.c#L211
> >
>
> You're right, sorry - I confused the general purpose PWM controller with the
> rather specific DISP_PWM controller (which does support polarity inversion).
>
> It's good - but I'd appreciate if you can please add a comment stating that
> the PWM values are inverted in SW because the controller does *not* support
> polarity inversion... so that next time someone looks at this will immediately
> understand what's going on and why :-)

so i would change comment like this:

		/* cooling level (0, 1, 2)
		 * signal is inverted on board
		 * mtk pwm driver does not support
		 * PWM_POLARITY_INVERTED */

> >>> +		pwms = <&pwm 0 10000>;
> >>> +		status = "okay";
> >>> +	};
> >>> +
> >>> +	phy14: ethernet-phy@14 {
..
> >>> +		interrupts-extended = <&pio 48 IRQ_TYPE_EDGE_FALLING>;
> >>> +		reset-gpios = <&pio 49 GPIO_ACTIVE_LOW>;
> >>> +		reset-assert-us = <10000>;
> >>> +		reset-deassert-us = <20000>;
> >>> +		phy-mode = "2500base-x";
> >>> +		full-duplex;
> >>> +		pause;
> >>> +		airoha,pnswap-rx;
> >>> +
> >>> +		leds {
> >>> +			#address-cells = <1>;
> >>> +			#size-cells = <0>;
> >>> +
> >>> +			led@0 { /* en8811_a_gpio5 */
> >>> +				reg = <0>;
> >>> +				color = <LED_COLOR_ID_YELLOW>;
> >>> +				function = LED_FUNCTION_LAN;
> >>> +				function-enumerator = <1>;
> >>
> >> Why aren't you simply using a label?
> >
> > You mean the comment? I can add it of course like for regulators.
> >
>
> I mean in place of the function-enumerator... that's practically used to
> distinguish between instances, it's not too common to see it, and usually
> "label" replaces exactly that - just that, instead of a different number,
> it gets a different name with no (usually) meaningless numbers :-)

as far as i understand using label also makes "function" property useless, after discussing
this with eric i would drop both on all 4 places by labels like these:

label = "yellow-lan";
label = "green-lan";
..

not sure if we should drop color property too...

> >>> +				default-state = "keep";
> >>> +				linux,default-trigger = "netdev";
> >>> +			};
> >>> +			led@1 { /* en8811_a_gpio4 */
> >>> +				reg = <1>;
> >>> +				color = <LED_COLOR_ID_GREEN>;
> >>> +				function = LED_FUNCTION_LAN;
> >>> +				function-enumerator = <2>;
> >>> +				default-state = "keep";
> >>> +				linux,default-trigger = "netdev";
> >>> +			};
> >>> +		};
> >>> +	};
> >>> +
> >>> +	phy15: ethernet-phy@15 {
> >>> +		reg = <15>;
> >>
> >> Same here.
> >>
> >> Cheers,
> >> Angelo

regards Frank