Quoting Linus Walleij (2018-07-09 06:54:01) > On Mon, Jul 2, 2018 at 7:56 PM Stephen Boyd <swb...@chromium.org> wrote: > > > I could do with some more clarity from Linus in the "Drivers needing > > both pin control and GPIOs" section of > > Documentation/driver-api/pinctl.rst but I read that section as stating > > that the GPIO driver needs to mux the pin as a GPIO by requesting the > > pinctrl backend to do so, unless the hardware overrides the muxed > > function selection when the GPIO is used, without involving pinctrl > > software. > > Yeah that text is especially terse :/ > > What it says (or what I meant to say) is that there is a choice > between letting the pin control and GPIO functionality on the > same pin be handled orthogonally or implementing these > gpio_*() callbacks into the pin control backend, but in either case > the two APIs must be used in sequence: > pin control setting comes first, second the GPIO subsystem can > request the GPIO line. > > I'll see if I can clarify. >
Ok. Is my interpretation correct though? The fundamental question here is if gpio_request() should remux the GPIO for the GPIO function or if drivers are expected to have pinmux settings to use their pin as a GPIO.
