On Thu, Apr 28, 2016 at 10:12 AM, Markus Pargmann <mpa@xxxxxxxxxxxxxx> wrote: > On Thursday 21 April 2016 13:08:21 Linus Walleij wrote: >> +Optionally, a GPIO controller may have a "gpio-line-names" property. This is >> +an array of strings defining the names of the GPIO lines going out of the >> +GPIO controller. This name should be the most meaningful producer name >> +for the system, such as a rail name indicating the usage. Package names >> +such as pin name are discouraged: such lines have opaque names (since they >> +are by definition generic purpose) and such names are usually not very >> +helpful. For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are >> +reasonable line names as they describe what the line is used for. "GPIO0" >> +is not a good name to give to a GPIO line. Placeholders are discouraged: > > "GPIO0" may not be a good name, but there are plenty of boards out there > that use just this line name in their schematic for GPIOs that are not > used otherwise. For example the riotboard has line-names "GPIO_1", > "GPIO4_31", "GPIO5_05", ... That is what is referred to as "rail name" above. If they really choose that name on a schematic, then it is the right name for it. >> + gpio-line-names = "MMC-CD", "MMC-WP", "VDD eth", "RST eth", "LED R", >> + "LED G", "LED B", "Col A", "Col B", "Col C", "Col D", >> + "Row A", "Row B", "Row C", "Row D", "NMI button", >> + "poweroff", "reset"; > > As many GPIO controllers have something like 32 GPIO lines, it can be > difficult to read which GPIO number the line "reset" is on. > But I think you can get around that by writing one name per file-line or > something similar. Also it should be immediately visible by listing all > gpio names in the userspace. Yeah well, the problem goes for clk-output-names that it's derived from as well, it comes from the DT syntactic limitations. >> + /* Empty strings are OK */ >> + if (ret < 0 && ret != -ENODATA) >> + dev_err(&gdev->dev, "unable to name line %d\n", >> + i); >> + } > > Maybe a warning for nstrings > ngpio here? Sure. Just waiting for DT maintainers and other stakeholders' input at this point. Yours, Linus Walleij -- 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
