Hi Vladimir, On Sun, Jun 11, 2017 at 10:57:18PM +0300, Vladimir Zapolskiy wrote: > Hi Oleksij, > > On 06/11/2017 09:19 AM, Oleksij Rempel wrote: > > Hi Rob, > > > > On Fri, Jun 09, 2017 at 10:41:30AM -0500, Rob Herring wrote: > >> On Fri, Jun 9, 2017 at 9:16 AM, Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote: > >>> This property is needed for barebox or may be other bootloaders > >>> to set proper gpio configuration as early as possible. > >>> > >>> This example is mainly based on "lines-initial-states" property > >>> from this binding documentation: > >>> Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > >> > >> Don't we have a binding for this already based on gpio-hogs. > > > > Markus Pargmann was working on this topic before and suddenly was not > > able to finish it. > > that's fine, but the proposed extension is supposedly not wanted. :( > > I found only some not finished discussions and no code or documentation > > in linux kernel upstream. > > > > So far, I was able to find fallowing patches and discussions: > > patch 23.08.2015, last comment 11.05.2017: > > https://patchwork.kernel.org/patch/7096721/ > > > > patch 23.02.2016, last comment 09.03.2016: > > https://patchwork.ozlabs.org/patch/586743/ > > > > Since there was objections about node-like design for gpio-initval, I > > provided an array property, which is similar to initval properties already used > > for different other device nodes. For example: > > > > Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt > > qcom,ath10k-calibration-data > > > > Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > lines-initial-states > > It'd rather be better to fix the drivers and remove the properties > from these found device tree binding descriptions. no sure if it is possible. WiFi calibration data is kind of initval too. > > > > Please fixme if I miss something. > > Why is GPIO hogging mechanism not good enough for your purpose? Becouse it should not permanently hog a gpio. The "Hogging" should be released as soon as some driver will request it. Right now, if I define gpio-hog, boot loader will configure it and start linux. But linux will never let it free. If you have other suggestions which fit to this use case, please tell me. I assume, right now I'm just blind. Other way, I can imagine is to create real device nodes which use this gpios. Compatible for this devices will be like this: some_gpio_holder: gpio@0 { compatible = "gpio-for-userspace"; gpio = <&gpio1 5 GPIO_ACTIVE_HIGH>; }; Boot loader will configure it as needed, an linux will do nothing with it so it can be used over /dev/gpio interface. > -- > With best wishes, > Vladimir -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- 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
