On Thu, Apr 27, 2017 at 4:56 PM, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > On Thu, Apr 27, 2017 at 11:19 AM, Jacopo Mondi > <jacopo+renesas@xxxxxxxxxx> wrote: >> Add bi-directional and output-enable pin configuration properties. >> >> bi-directional allows to specify when a pin shall operate in input and >> output mode at the same time. This is particularly useful in platforms >> where input and output buffers have to be manually enabled. >> >> output-enable is just syntactic sugar to specify that a pin shall >> operate in output mode, ignoring the provided argument. >> This pairs with input-enable pin configuration option. > > For me it looks like you are trying to alias open-drain + bias or > alike. Don't actually see the benefit of it. Andy is bringing up a valid point. And I remember asking about this before. What does "bi-directional" really mean, electrically speaking? Does is just mean open drain and/or open source actually? (See Documentation/gpio/driver.txt for an explanation of how open drain/source works.) When you set an output without setting a value, what happens electrically? Isn't this bias-high-impedance / High-Z? Hopefully you can find the answer from Renesas hardware dept. You can certainly call it whatever the datasheet calls it in your driver #defines but for the DT bindings we would ideally have the physical world things. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
