Subject: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add subnode for LED configuration

From: Matthias Kaehlcke <[email-masked]>
Date: Fri, 2 Aug 2019 11:27:37 -0700

On Fri, Aug 02, 2019 at 06:57:55PM +0200, Andrew Lunn wrote:
> On Thu, Aug 01, 2019 at 12:07:56PM -0700, Matthias Kaehlcke wrote:
> > The LED behavior of some Ethernet PHYs is configurable. Add an
> > optional 'leds' subnode with a child node for each LED to be
> > configured. The binding aims to be compatible with the common
> > LED binding (see devicetree/bindings/leds/common.txt).
> > 
> > A LED can be configured to be 'on' when a link with a certain speed
> > is active, or to blink on RX/TX activity. For the configuration to
> > be effective it needs to be supported by the hardware and the
> > corresponding PHY driver.
> > 
> > Suggested-by: Andrew Lunn <[email-masked]>
> > Signed-off-by: Matthias Kaehlcke <[email-masked]>
> > ---
> > Changes in v4:
> > - patch added to the series
> > ---
> >  .../devicetree/bindings/net/ethernet-phy.yaml | 47 +++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > index f70f18ff821f..81c5aacc89a5 100644
> > --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > @@ -153,6 +153,38 @@ properties:
> >        Delay after the reset was deasserted in microseconds. If
> >        this property is missing the delay will be skipped.
> >  
> > +patternProperties:
> > +  "^leds$":
> > +    type: object
> > +    description:
> > +      Subnode with configuration of the PHY LEDs.
> > +
> > +    patternProperties:
> > +      "^led@[0-9]+$":
> > +        type: object
> > +        description:
> > +          Subnode with the configuration of a single PHY LED.
> > +
> > +    properties:
> > +      reg:
> > +        description:
> > +          The ID number of the LED, typically corresponds to a hardware ID.
> > +        $ref: "/schemas/types.yaml#/definitions/uint32"
> > +
> > +      linux,default-trigger:
> > +        description:
> > +          This parameter, if present, is a string specifying the trigger
> > +          assigned to the LED. Supported triggers are:
> > +            "phy_link_10m_active" - LED will be on when a 10Mb/s link is active
> > +            "phy_link_100m_active" - LED will be on when a 100Mb/s link is active
> > +            "phy_link_1g_active" - LED will be on when a 1Gb/s link is active
> > +            "phy_link_10g_active" - LED will be on when a 10Gb/s link is active
> > +            "phy_activity" - LED will blink when data is received or transmitted
> 
> Matthias
> 
> We should think a bit more about these names.
> 
> I can see in future needing 1G link, but it blinks off when there is
> active traffic? So phy_link_1g_active could be confusing, and very similar to
> phy_link_1g_activity?

agreed, the 'active' vs' 'activity' can be confusing, let's avoid that.

> So maybe 

> > +            "phy_link_10m" - LED will be solid on when a 10Mb/s link is active
> > +            "phy_link_100m" - LED will be solid on when a 100Mb/s link is active
> > +            "phy_link_1g" - LED will be solid on when a 1Gb/s link is active
> 
> etc.
>
> And then in the future we can have
> 
>                "phy_link_1g_activity' - LED will be on when 1Gbp/s
>                                         link is active and blink off
>                                         with activity.

sounds good to me

> What other use cases do we have? I don't want to support everything,
> but we should be able to represent the most common modes without the
> names getting too confusing.

Initially I planned to support to configure a LED to be solid for
multiple link speeds, however that could become a bit messy with the
string based triggers, unless we limit the possible combinations. My
expertise in network land is limited, so I'm not sure if that's an
important/realistic use case.