netdev - Re: [PATCH 1/2] dt-bindings: dp83867: define ti, ledX-active-low properties

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Message-ID: <23673049.ouqheUzb2q@steina-w>
Date:   Fri, 04 Nov 2022 09:11:11 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 1/2] dt-bindings: dp83867: define ti, ledX-active-low properties

Am Freitag, 4. November 2022, 08:17:44 CET schrieb Rasmus Villemoes:
> On 03/11/2022 23.17, Andrew Lunn wrote:
> > On Thu, Nov 03, 2022 at 03:31:17PM +0100, Rasmus Villemoes wrote:
> >> The dp83867 has three LED_X pins that can be used to drive LEDs. They
> >> are by default driven active high, but on some boards the reverse is
> >> needed. Add bindings to allow a board to specify that they should be
> >> active low.
> > 
> > Somebody really does need to finish the PHY LEDs via /sys/class/leds.
> > It looks like this would then be a reasonable standard property:
> > active-low, not a vendor property.
> > 
> > Please help out with the PHY LEDs patches.
> 
> So how do you imagine this to work in DT? Should the dp83867 phy node
> grow a subnode like this?
> 
>   leds {
>     #address-cells = <1>;
>     #size-cells = <0>;
> 
>     led@0 {
>       reg = <0>;
>       active-low;
>     };
>     led@2 {
>       reg = <2>;
>       active-low;
>     };
>   };
> 
> Since the phy drives the leds automatically based on (by default)
> link/activity, there's not really any need for a separate LED driver nor
> do I see what would be gained by somehow listing the LEDs in
> /sys/class/leds. Please expand.

There have been several tries to support LED support directly per DT, e.g. [1] 
& [2]. I assume Andrew is referring to [3].

Best regards,
Alexander

[1] https://lore.kernel.org/netdev/YFUVcLCzONhPmeh8@lunn.ch/T/
[2] https://www.spinics.net/lists/netdev/msg677827.html
[3] https://patches.linaro.org/project/linux-leds/cover/
20220503151633.18760-1-ansuelsmth@...il.com/