Hi all I'm confused by the ways to specify GPIO polarity in general and for MMC card-detect and write-protect pins specifically. IIUC, the flags variable as returned by a call to of_get_named_gpio_flags(..., &flags) should be platform-independent, if a specific gpio driver choses to define their gpio cells in a non-standard way, not according to "*-gpios = <&gpio gpio_number flags>" they shall be providing an .of_xlate() method to convert whatever their GPIO information to standard data. So far the GPIO subsystem defines only one flag OF_GPIO_ACTIVE_LOW. Any other use of the above flags is invalid. The first confusing thing about those flags is, that they are defined as an enum, and not as a bit-field. This seems to suggest, that one only should be comparing flags to specific enum values, and not checking set bits, like e.g. drivers/usb/host/ohci-at91.c and drivers/hwmon/gpio-fan.c are doing. Logically, this should indeed be a bit-field, in which case of_get_named_gpio_flags()'s prototype should be changed, as well as the definition of OF_GPIO_ACTIVE_LOW. Secondly, drivers/pinctrl/pinctrl-nomadik.c seems to be doing a wrong thing - they are defining extended incompatible flags' bits in Documentation/devicetree/bindings/gpio/gpio-nmk.txt and not providing an .of_xlate() method. All drivers quoted above are just examples, that I stumbled ver, while trying to figure out what's the right way to use flags and how others do that. There are most likely more of them in the tree. Thirdly, Documentation/devicetree/bindings/mmc/mmc.txt defines the use of gpio-bindings: - cd-gpios: Specify GPIOs for card detection, see gpio binding - wp-gpios: Specify GPIOs for write protection, see gpio binding but additionally defines two boolean properties: - cd-inverted: when present, polarity on the cd gpio line is inverted - wp-inverted: when present, polarity on the wp gpio line is inverted which should be redundant and instead GPIO flags should be used? Are my above conclusions correct and what should we do to improve the situation? Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
