On Mon, Feb 12, 2024 at 02:38:27PM +0100, Krzysztof Kozlowski wrote: > On 12/02/2024 12:58, Ralf Schlatterbeck wrote: > > On Mon, Feb 12, 2024 at 12:25:48PM +0100, Krzysztof Kozlowski wrote: > >> > >> Hm, I don't understand how exactly it helps. The GPIO expander has its > >> own example and as you pointed below, this is basically the same code, > >> except rw and backlight GPIOs. > > > > The hd44780 is a display that is very often used. > > GPIO expanders and their usage is nothing specific to this device - > other devices also might benefit of them. Or the SoCs which have enough > of GPIOs... I really do not understand why do we need expander here and > how does it help The hd44780 is most often sold together with that specific I/O expander. The idea was to help people with that combination how to get their device working. > Anyway, binding examples should not be collection of unrelated > solutions, because then we should accept for each device schema several > other variations and combinations. The solutions in that case are not unrelated because they document the most-often-used hw combo. I also didn't find any documentation of how to actually *use* the pcf8575 I/O expander. Even Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml has only docs on how to instantiate the device on the i2c bus but not how then to use the I/Os of the chip for something else. So I'd ask again to not remove that piece of useful documentation. And to get somehow philosophic: I think that docs should be didactic, not optimized to the least redundancy. Thanks and kind regards, Ralf -- Dr. Ralf Schlatterbeck Tel: +43/2243/26465-16 Open Source Consulting www: www.runtux.com Reichergasse 131, A-3411 Weidling email: office@xxxxxxxxxx
