On Thursday 10 March 2016 12:37:32 Laxman Dewangan wrote: > > On Wednesday 09 March 2016 10:47 PM, Stephen Warren wrote: > > On 03/09/2016 06:20 AM, Laxman Dewangan wrote: > >> > >> On Wednesday 09 March 2016 11:58 AM, Markus Pargmann wrote: > >>> * PGP Signed by an unknown key > >>> > >>> Hi, > >>> > >>> On Tue, Mar 08, 2016 at 05:32:07PM +0530, Laxman Dewangan wrote: > >>>> The child node for gpio hogs under gpio controller's node > >>>> provide the mechanism to automatic GPIO request and > >>>> configuration as part of the gpio-controller's driver > >>>> probe function. > >>>> > >>>> Currently, property "gpio" takes one gpios for such > >>>> configuration. Add support to have multiple GPIOs in > >>>> this property so that multiple GPIOs of gpio-controller > >>>> can be configured by this mechanism with one child node. > >>> So if I read this correctly you want to have multiple GPIOs with the > >>> same line name? Why don't you use multiple child nodes with individual > >>> line names? > >>> > >> There is cases on which particular functional configuration needs sets > >> of GPIO to set. On this case, making sub node for each GPIOs creates > >> lots of sub-nodes and add complexity on readability, usability and > >> maintainability. > >> Example: for my board, I wanted to set GPIO H2 to input and H0 and H1 to > >> be output high. > >> Instead of three nodes, I can have two here: > >> gpio@0,6000d000 { > >> wlan_input { > >> gpio-hog; > >> gpios = <TEGRA_GPIO(H, 2) 0>; > >> input; > >> }; > >> > >> wlan_output { > >> gpio-hog; > >> gpios = <TEGRA_GPIO(H, 0) 0 TEGRA_GPIO(H, 1) 0>; > >> output-high; > >> }; > >> }; > > > > >> So here I am grouping the multiple output GPIO together. > >> > >> This looks much similar if we have many GPIOs for one type of > >> configurations. > >> > >> Even it looks better if we have something: > >> gpio@0,6000d000 { > >> wlan_control { > >> gpio-hog; > >> gpios-input = <TEGRA_GPIO(H, 2) 0>; > >> gpios-output-high = <TEGRA_GPIO(H, 0) 0 > >> TEGRA_GPIO(H, 1) 0>; > >> }; > >> }; > > > > The problem with that is the description used when acquiring the GPIO > > is just "wlan_input", "wlan_output", or "wlan_control". There's > > nothing to indicate what those individual pins do (perhaps one is a > > reset signal, one is a regulator enable, etc.?) By requiring separate > > nodes for each GPIO, then the node name can provide a meaningful > > semantic name/description for each GPIO, which provides much more > > information. > > > > On this case, we have already property "line-name" and passed the name > of the gpio via this property. > The property names is "line-name" which is good for one string. We can > support other property "line-names" with multiple string per GPIO index. > > line-names = "wlan-reset", "wlan-enable"; There is currently a discussion about the future bindings for subnodes in GPIO controller nodes. Please have a look at these two mail threads: "Device tree binding documentation for gpio-switch" "gpio: of: Add support to have multiple gpios in gpio-hog" Best Regards, Markus > > > > If the approach in this patch is acceptable though, I think you want > > to update the description of "gpios" (in the GPIO hog definition > > section) in Documentation/devicetree/bindings/gpio/gpio.txt to mention > > that multiple GPIO entries are legal. Right now it says that property > > much contain exactly #gpio-cells, not a multiple of #gpio-cells. > > I have 5th patch for this and will rearrange series as you suggested on > 5th patch. > > > -- 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