From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laxman Dewangan Subject: Re: [PATCH 4/5] gpio: of: Add support to have multiple gpios in gpio-hog Date: Thu, 10 Mar 2016 12:37:32 +0530 Message-ID: <56E11D34.60401@nvidia.com> References: <1457438528-29054-1-git-send-email-ldewangan@nvidia.com> <1457438528-29054-5-git-send-email-ldewangan@nvidia.com> <20160309062849.GB10454@pengutronix.de> <56E02335.6020901@nvidia.com> <56E05AA9.8000503@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56E05AA9.8000503-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: Markus Pargmann , linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, Benoit Parrot , Alexandre Courbot List-Id: linux-gpio@vger.kernel.org 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 = ; >> input; >> }; >> >> wlan_output { >> gpio-hog; >> gpios = ; >> 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 = ; >> gpios-output-high = > 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"; > 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. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html