On Thu, Feb 27, 2014 at 10:47:58AM -0700, Stephen Warren wrote: > On 02/27/2014 10:38 AM, Gross, Mark wrote: > > Please know that no one should not consider me an authority on ACPI at this > > time. But, I have some comments / context / thoughts below. > > > > Also I apologize in advance for any email formatting issues caused by > > replying to this via my work exchange account / outlook client. Folks can > > use mgross@xxxxxxxxxxxxxxx to avoid outlook-isms from me in the future. > > > >> -----Original Message----- > >> From: Linus Walleij [mailto:linus.walleij@xxxxxxxxxx] > >> Sent: Tuesday, February 25, 2014 1:14 AM > >> To: Stephen Warren; Alexandre Courbot; Grant Likely; > >> devicetree@xxxxxxxxxxxxxxx > >> Cc: Chen-Yu Tsai; Heikki Krogerus; Johannes Berg; David S. Miller; Rhyland > >> Klein; linux-wireless; netdev; linux-kernel; Arnd Bergmann; Gross, Mark > >> Subject: Re: [PATCH 2/4] net: rfkill: gpio: remove gpio names > >> > >> On Fri, Feb 21, 2014 at 6:35 AM, Stephen Warren > >> <swarren@xxxxxxxxxxxxx> wrote: > >>> On 02/20/2014 06:55 PM, Chen-Yu Tsai wrote: > >> > >>>> That's correct. However using con_id to pass this results in > >>>> different behavior across DT and ACPI. A better way is to export the > >>>> labeling function so consumers can set meaningful labels themselves. > >>> > >>> But this code is the consumer of those GPIOs. IF the parameter to > >>> devm_gpiod_get_index() isn't intended to be used, why does it exist? > >> > >> Kerneldoc says: > >> > >> /** > >> * gpiod_get_index - obtain a GPIO from a multi-index GPIO function > >> * @dev: GPIO consumer, can be NULL for system-global GPIOs > >> * @con_id: function within the GPIO consumer > >> * @idx: index of the GPIO to obtain in the consumer > >> * > >> > >> Basically it is just exposing the fact that of_find_gpio() and > >> acpi_find_gpio() both take a con_id as argument. > >> > >> If we drill into this, we find that it is used to conjure the arbitrary string > >> before the gpios in the DT case, like: > >> > >> foo-gpios = <...>; > >> > >> As in tegra30-beaver.dts... > >> > >> sdhci@78000000 { > >> status = "okay"; > >> cd-gpios = <&gpio TEGRA_GPIO(I, 5) GPIO_ACTIVE_LOW>; > >> wp-gpios = <&gpio TEGRA_GPIO(T, 3) GPIO_ACTIVE_HIGH>; > >> power-gpios = <&gpio TEGRA_GPIO(D, 7) GPIO_ACTIVE_HIGH>; > >> bus-width = <4>; > >> }; > >> > >> Instead of passing the GPIOs as index 0,1,2 they are named and I do admit > >> this has a nice "things are under control" aspect to it. > > > > [Gross, Mark] FWIW I don't think this is as "under control" as you do. Those > > names in the above sdhci example are derived from a specific SDHCI > tegra spec > > sheet or schematic. Those names likely come from the data sheet for > > the controller. > > The names of the properties are fixed and defined by the DT binding for > the Tegra SDHCI controller, or even the core SDHCI bindings. Hence, they > will be the same in every DT file that uses that Tegra SDHCI compatible > value (the compatible property isn't show above, because the above > fragment is a board.dts file, and the compatible value gets inherited > from the soc.dtsi file). There won't be any variation at all, > irrespective of what signal names exist in a particular board schematic. > > If there were ever an (upstream?) ACPI "binding"(?) for the Tegra SDHCI > controller, I would hope it would use the exact same names for the GPIO > signals. me to! --mark -- 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
