On 16/04/2023 13:33, Andy Shevchenko wrote: > On Sun, Apr 16, 2023 at 2:21 PM Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> On 16/04/2023 13:14, Andy Shevchenko wrote: >>> On Sun, Apr 16, 2023 at 2:04 PM Krzysztof Kozlowski >>> <krzysztof.kozlowski@xxxxxxxxxx> wrote: >>>> On 16/04/2023 11:36, Andy Shevchenko wrote: >>>>> On Sun, Apr 16, 2023 at 10:42 AM Krzysztof Kozlowski >>>>> <krzysztof.kozlowski@xxxxxxxxxx> wrote: >>>>>> On 15/04/2023 17:06, Andy Shevchenko wrote: >>>>>>> On Fri, Apr 14, 2023 at 9:37 AM Alexander Stein >>>>>>> <alexander.stein@xxxxxxxxxxxxxxx> wrote: >>>>>>>> Am Dienstag, 11. April 2023, 11:34:16 CEST schrieb Andy Shevchenko: >>>>>>>>> On Tue, Apr 11, 2023 at 10:19 AM Alexander Stein >>>>>>>>> <alexander.stein@xxxxxxxxxxxxxxx> wrote: >>>>> >>>>> ... >>>>> >>>>>>>>> So, taking the above into consideration, why is it GPIO property to >>>>>>>>> begin with? This is PCB property of the certain platform design that >>>>>>>>> needs to be driven by a specific driver, correct? >>>>>>>> >>>>>>>> True this is induced by the PCB, but this property applies to the GPIO, >>>>>>>> neither the GPIO controller output, nor the GPIO consumer is aware of. >>>>>>>> So it has to be added in between. The original idea to add a property for the >>>>>>>> consumer driver is also rejected, because this kind of behavior is not limited >>>>>>>> to this specific driver. >>>>>>>> That's why the delay is inserted in between the GPIO output and GPIO consumer. >>>>>>>> >>>>>>>>> At the very least this is pin configuration (but external to the SoC), >>>>>>>>> so has to be a _separate_ pin control in my opinion. >>>>>>>> >>>>>>>> Sorry, I don't get what you mean by _separate_ pin control. >>>>>>> >>>>>>> As you mentioned above this can be applied theoretically to any pin of >>>>>>> the SoC, That pin may or may not be a GPIO or a pin that can be >>>>>>> switched to the GPIO mode. Hence this entire idea shouldn't be part of >>>>>>> the existing _in-SoC_ pin control driver if any. This is a purely >>>>>>> separate entity, but at the same time it adds a property to a pin, >>>>>>> hence pin control. >>>>>>> At the same time, it's not an SoC related one, it's a PCB. Hence _separate_. >>>>>> >>>>>> I don't think that anything here is related to pin control. Pin control >>>>>> is specific function of some device which allows different properties or >>>>>> different functions of a pin. >>>>> >>>>> Sorry, but from a hardware perspective I have to disagree with you. >>>>> It's a property of the _pin_ and not of a GPIO. Any pin might have the >>>>> same property. That's why it's definitely _not_ a property of GPIO, >>>>> but wider than that. >>>> >>>> I did not say this is a property of GPIO. I said this is nothing to do >>>> with pin control, configuration and pinctrl as is. >>> >>> Ah, I see. But still is a property of the pin on the PCB level. >> >> No, it is property of a circuit, so property of two pins and a wire >> between them. Not a property of one pin. > > Electrically speaking -- yes, software speaking, no, this is the > property of the one end (platfrom abstraction in the software) and as > you said, consumer which may be SoC, or the device connected to the > SoC (depending on the signal direction), or both (like pull-up for > I2C). > >>> That's >>> why I said that it should be like a "proxy" driver that has to be a >>> consumer of the pins on one side and provide the pins with this >>> property on the other. >> >> Not sure, why do you need it for anything else than GPIOs? What is the >> real world use case for proxy driver of non-GPIO lines? > > I2C is an example where we have something in between, which both of Are you sure you have RC (not just resistor) in I2C? > the ends are using and this is the property of PCB, but luckily we > don't need anything special in the software for that, right? But from > the electrical point of view it's exactly a non-GPIO property. That's > why "proxy". Still I do not see any reason to call it anything else than GPIO. If you think that there is any other usage, please bring it as an real, non-theoretical example. Best regards, Krzysztof
