Re: [PATCH v7 11/11] dt-bindings: net: dsa: qca8k: add LEDs definition example

[Rob Herring <robh@kernel.org>]

On Wed, Dec 21, 2022 at 6:55 AM Christian Marangi <ansuelsmth@gmail.com> wrote:
>
> On Wed, Dec 21, 2022 at 02:41:50AM +0100, Andrew Lunn wrote:
> > > > > +                        };
> > > > > +
> > > > > +                        led@1 {
> > > > > +                            reg = <1>;
> > > > > +                            color = <LED_COLOR_ID_AMBER>;
> > > > > +                            function = LED_FUNCTION_LAN;
> > > > > +                            function-enumerator = <1>;
> > > >
> > > > Typo? These are supposed to be unique. Can't you use 'reg' in your case?
> > >
> > > reg in this context is the address of the PHY on the MDIO bus. This is
> > > an Ethernet switch, so has many PHYs, each with its own address.
> >
> > Actually, i'm wrong about that. reg in this context is the LED number
> > of the PHY. Typically there are 2 or 3 LEDs per PHY.
> >
> > There is no reason the properties need to be unique. Often the LEDs
> > have 8 or 16 functions, identical for each LED, but with different
> > reset defaults so they show different things.
> >
>
> Are we taking about reg or function-enumerator?
>
> For reg it's really specific to the driver... My idea was that since a
> single phy can have multiple leds attached, reg will represent the led
> number.
>
> This is an example of the dt implemented on a real device.
>
>                 mdio {
>                         #address-cells = <1>;
>                         #size-cells = <0>;
>
>                         phy_port1: phy@0 {
>                                 reg = <0>;
>
>                                 leds {
>                                         #address-cells = <1>;
>                                         #size-cells = <0>;
>
>                                         lan1_led@0 {
>                                                 reg = <0>;
>                                                 color = <LED_COLOR_ID_WHITE>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <1>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>
>                                         lan1_led@1 {
>                                                 reg = <1>;
>                                                 color = <LED_COLOR_ID_AMBER>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <1>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>                                 };
>                         };
>
>                         phy_port2: phy@1 {
>                                 reg = <1>;
>
>                                 leds {
>                                         #address-cells = <1>;
>                                         #size-cells = <0>;
>
>
>                                         lan2_led@0 {
>                                                 reg = <0>;
>                                                 color = <LED_COLOR_ID_WHITE>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <2>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>
>                                         lan2_led@1 {
>                                                 reg = <1>;
>                                                 color = <LED_COLOR_ID_AMBER>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <2>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>                                 };
>                         };
>
>                         phy_port3: phy@2 {
>                                 reg = <2>;
>
>                                 leds {
>                                         #address-cells = <1>;
>                                         #size-cells = <0>;
>
>                                         lan3_led@0 {
>                                                 reg = <0>;
>                                                 color = <LED_COLOR_ID_WHITE>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <3>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>
>                                         lan3_led@1 {
>                                                 reg = <1>;
>                                                 color = <LED_COLOR_ID_AMBER>;
>                                                 function = LED_FUNCTION_LAN;
>                                                 function-enumerator = <3>;
>                                                 linux,default-trigger = "netdev";
>                                         };
>                                 };
>                         };
>
> In the following implementation. Each port have 2 leds attached (out of
> 3) one white and one amber. The driver parse the reg and calculate the
> offset to set the correct option with the regs by also checking the phy
> number.

Okay, the full example makes more sense. But I still thought
'function-enumerator' values should be globally unique within a value
of 'function'. Maybe Jacek has an opinion on this?

You are using it to distinguish phys/ports, but there's already enough
information in the DT to do that. You have the parent nodes and I
assume you have port numbers under 'ethernet-ports'. For each port,
get the phy node and then get the LEDs.

> An alternative way would be set the reg to be the global led number in
> the switch and deatch the phy from the calculation.
>
> Something like
> port 0 led 0 = reg 0
> port 0 led 1 = reg 1
> port 1 led 0 = reg 2
> port 1 led 1 = reg 3
> ...

No.

Rob