| Message ID | 20240420-adin-pin-polarity-v2-1-bf9714da7648@solid-run.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: phy: adin: add support for setting led-, link-status-pin polarity | expand |
> + adi,link-st-polarity: > + $ref: /schemas/types.yaml#/definitions/uint32 > + description: > + LINK_ST pin polarity. > + enum: > + - 0 # active high > + - 1 # active low > + default: 0 > + How does this differ from: Documentation/devicetree/bindings/leds/common.yaml + active-low: + type: boolean + description: + Makes LED active low. To turn the LED ON, line needs to be + set to low voltage instead of high. Why do we need a vendor property when there is a generic property? Andrew
Am 20.04.24 um 18:10 schrieb Andrew Lunn: >> + adi,link-st-polarity: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: >> + LINK_ST pin polarity. >> + enum: >> + - 0 # active high >> + - 1 # active low >> + default: 0 >> + > How does this differ from: > > Documentation/devicetree/bindings/leds/common.yaml > > + active-low: > + type: boolean > + description: > + Makes LED active low. To turn the LED ON, line needs to be > + set to low voltage instead of high. > > > Why do we need a vendor property when there is a generic property? It differs in tree depth and naming. To use led binding we need to add a leds node with a led node inside, and decide on an index for this not-an-led pin. Sure, could be done but maybe should be documented somewhere as it is not intuitive. Main reason for having a vendor-specific and non-led property is that this pin is not a led, it is merely a signal. The PHY can be configured to provide via this signal either: - link-status - collision detection - carrier sense - tx packet start - rx packet start The purpose of the binding I propose is just polarity of this signal. A more complete binding would also allow selection from the above listed functions. This kind of configuration is much more like pinctrl than led.
> Main reason for having a vendor-specific and non-led property > is that this pin is not a led. So you are not driving an LED with its? What are you using it for? > This kind of configuration is much more like pinctrl than led. So what is the pinctrl way of describing this? You should not be inventing something new if there is an existing mechanism to describe it. We want consistency, not 42 different ways of doing one thing. Andrew
Am 20.04.24 um 19:09 schrieb Andrew Lunn: >> Main reason for having a vendor-specific and non-led property >> is that this pin is not a led. > So you are not driving an LED with its? What are you using it for? The unit I am currently working on connects an LED, yes. Therefore I agree with you that it could be described adequately by an led node with active-low property. I merely don't like the idea that this makes no sense for the other possible pin functions. Once somebody uses this pin for different use-case, they will need to solve it again. >> This kind of configuration is much more like pinctrl than led. > > So what is the pinctrl way of describing this? You should not be > inventing something new if there is an existing mechanism to describe > it. We want consistency, not 42 different ways of doing one thing. I am mostly familiar with the #define PIN_FUNCTION magic-numbers pins = <PIN_FUNCTION more-magic-numbers>; But on Marvell platforms there is: marvell,pins = "mpp1"; marvell,function = "gpio"; I also found more generic???: Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml Documentation/devicetree/bindings/pinctrl/pinmux-node.yaml which have output-high/output-low, function, pin. Interestingly LED_0 supports some non-led functions, too: - collision detection - carrier sense - tx/rx start - tx error so polarity is also relevant to non-led usage of LED_0 pin. Might be I am not seeing the big picture how this fits a generic structure.
> I merely don't like the idea that this makes no sense for the other > possible pin functions. > Once somebody uses this pin for different use-case, they will need > to solve it again. There are not too many different uses of this pin. The data sheet indicates you can connect it to the MAC to indicate link. You might also be able to use it with an external PTP stamper, using the start of frame indication. I don't know of any bindings for such use case, but something will be needed to describe how the pin is connected to the other device. And at that point, the active low property could be used. > >> This kind of configuration is much more like pinctrl than led. > > > > So what is the pinctrl way of describing this? You should not be > > inventing something new if there is an existing mechanism to describe > > it. We want consistency, not 42 different ways of doing one thing. > I am mostly familiar with the > #define PIN_FUNCTION magic-numbers > pins = <PIN_FUNCTION more-magic-numbers>; > > But on Marvell platforms there is: > marvell,pins = "mpp1"; > marvell,function = "gpio"; > > I also found more generic???: > Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml > Documentation/devicetree/bindings/pinctrl/pinmux-node.yaml > which have output-high/output-low, function, pin. So that is probably your alternative if you want to not use the LED binding. > > Interestingly LED_0 supports some non-led functions, too: > - collision detection > - carrier sense > - tx/rx start > - tx error > so polarity is also relevant to non-led usage of LED_0 pin. Collision detection is an LED usage, you just don't see it very often since half duplex is pretty unusual this century. Carrier sense is also similar age, from when Ethernet was CSMA/CD. Since they are not really used any more we don't have them in the LED framework, but i think we could implement them if somebody actually wanted them. My intention was to keep the LED framework KISS, since vendors tend to implement all sorts of odd LED blink reasons. But if nobody wants them, nobody has a good end user use case for them, why support them? Andrew
Am 21.04.24 um 19:54 schrieb Andrew Lunn: >> I merely don't like the idea that this makes no sense for the other >> possible pin functions. >> Once somebody uses this pin for different use-case, they will need >> to solve it again. > There are not too many different uses of this pin. The data sheet > indicates you can connect it to the MAC to indicate link. You might > also be able to use it with an external PTP stamper, using the start > of frame indication. > > I don't know of any bindings for such use case, but something will be > needed to describe how the pin is connected to the other device. And > at that point, the active low property could be used. > >>>> This kind of configuration is much more like pinctrl than led. >>> >>> So what is the pinctrl way of describing this? You should not be >>> inventing something new if there is an existing mechanism to describe >>> it. We want consistency, not 42 different ways of doing one thing. >> I am mostly familiar with the >> #define PIN_FUNCTION magic-numbers >> pins = <PIN_FUNCTION more-magic-numbers>; >> >> But on Marvell platforms there is: >> marvell,pins = "mpp1"; >> marvell,function = "gpio"; >> >> I also found more generic???: >> Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml >> Documentation/devicetree/bindings/pinctrl/pinmux-node.yaml >> which have output-high/output-low, function, pin. > So that is probably your alternative if you want to not use the LED > binding. I will consider using pincfg/-mux > >> Interestingly LED_0 supports some non-led functions, too: >> - collision detection >> - carrier sense >> - tx/rx start >> - tx error >> so polarity is also relevant to non-led usage of LED_0 pin. > Collision detection is an LED usage, you just don't see it very often > since half duplex is pretty unusual this century. Carrier sense is > also similar age, from when Ethernet was CSMA/CD. > > Since they are not really used any more we don't have them in the LED > framework, but i think we could implement them if somebody actually > wanted them. My intention was to keep the LED framework KISS, since > vendors tend to implement all sorts of odd LED blink reasons. But if > nobody wants them, nobody has a good end user use case for them, why > support them? I see. So in fact most functions I wanted to enable muxing are LED functions, leaving only some specifically for pinmux. I believe pinmux is more correct, but there is overlap with led function. I will try to find some time for 1. describing both signals as LEDs, taking care of active-low 2. look into using pinmux (lower priority). I think this would be more interesting to bigger phys with more muxable signals, adin1300 is rather small. Thank you for all the comments!
diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml index 929cf8c0b0fd..cf195e070b26 100644 --- a/Documentation/devicetree/bindings/net/adi,adin.yaml +++ b/Documentation/devicetree/bindings/net/adi,adin.yaml @@ -52,6 +52,15 @@ properties: description: Enable 25MHz reference clock output on CLK25_REF pin. type: boolean + adi,link-st-polarity: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + LINK_ST pin polarity. + enum: + - 0 # active high + - 1 # active low + default: 0 + unevaluatedProperties: false examples:
ADIN1200/1300 support software control over LINK_ST pin polarity. This is a fixed function output reflecting phy link-status that is not otherwise controllable by software. Add new property adi,link-st-polarity for specifying polarity as either active-high (reset-default) or active-low. Signed-off-by: Josua Mayer <josua@solid-run.com> --- Documentation/devicetree/bindings/net/adi,adin.yaml | 9 +++++++++ 1 file changed, 9 insertions(+)